updated to Roslyn 2.11.0-beta1-final

[filipw]

Fixes #1364
Additionally, added C# 8.0 to the language version converter and added a test to verify that scripting defaults to C# 8.0 (it should always use latest version).

I think this should only be merged after we release a new version from master, as master has Roslyn 2.10.0 and we have not yet released a 2.10.0-based OmniSharp.

[filipw]

Looks like this works on Windows, but on Mono fails with the following stack

System.TypeLoadException: Could not load type of field 'Microsoft.CodeAnalysis.SQLite.Interop.SqlConnection:_handle' (0) due to: Could not load file or assembly 'SQLitePCLRaw.core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=1488e028ca7ab535' or one of its dependencies.
  at (wrapper managed-to-native) System.RuntimeType.GetPropertiesByName_native(System.RuntimeType,intptr,System.Reflection.BindingFlags,bool)
  at System.RuntimeType.GetPropertiesByName (System.String name, System.Reflection.BindingFlags bindingAttr, System.Boolean icase, System.RuntimeType reflectedType) [0x0001b] in <0f8aeac9d63d4b8aa575761bb4e65b79>:0 
  at System.RuntimeType.GetPropertyCandidates (System.String name, System.Reflection.BindingFlags bindingAttr, System.Type[] types, System.Boolean allowPrefixLookup) [0x00010] in <0f8aeac9d63d4b8aa575761bb4e65b79>:0 
  at System.RuntimeType.GetProperties (System.Reflection.BindingFlags bindingAttr) [0x00000] in <0f8aeac9d63d4b8aa575761bb4e65b79>:0 
  at System.Reflection.RuntimeReflectionExtensions.GetRuntimeProperties (System.Type type) [0x00006] in <0f8aeac9d63d4b8aa575761bb4e65b79>:0 
  at System.Composition.TypedParts.Discovery.TypeInspector+<DiscoverPropertyExports>d__7.MoveNext () [0x00030] in <9aac21a4a3f24063b2b8b59143acddfc>:0 
  at System.Composition.TypedParts.Discovery.TypeInspector+<DiscoverExports>d__5.MoveNext () [0x000dc] in <9aac21a4a3f24063b2b8b59143acddfc>:0 
  at System.Composition.TypedParts.Discovery.TypeInspector.InspectTypeForPart (System.Reflection.TypeInfo type, System.Composition.TypedParts.Discovery.DiscoveredPart& part) [0x00061] in <9aac21a4a3f24063b2b8b59143acddfc>:0 
  at System.Composition.TypedParts.TypedPartExportDescriptorProvider..ctor (System.Collections.Generic.IEnumerable`1[T] types, System.Composition.Convention.AttributedModelProvider attributeContext) [0x00037] in <9aac21a4a3f24063b2b8b59143acddfc>:0 
  at System.Composition.Hosting.ContainerConfiguration.CreateContainer () [0x00042] in <9aac21a4a3f24063b2b8b59143acddfc>:0 
  at Microsoft.CodeAnalysis.Host.Mef.MefHostServices.Create (System.Collections.Generic.IEnumerable`1[T] assemblies) [0x00052] in <584f9e64c3434f96bb53a5fb697dcadf>:0 
  at OmniSharp.HostServicesAggregator.CreateHostServices () [0x00000] in <2c158e114ee34d36a470a54c234f4f73>:0 
  at OmniSharp.OmniSharpWorkspace..ctor (OmniSharp.HostServicesAggregator aggregator, Microsoft.Extensions.Logging.ILoggerFactory loggerFactory, OmniSharp.FileWatching.IFileSystemWatcher fileSystemWatcher) [0x0000b] in <2c158e114ee34d36a470a54c234f4f73>:0 
  at (wrapper dynamic-method) System.Object.lambda_method(System.Runtime.CompilerServices.Closure,System.Composition.Hosting.Core.LifetimeContext,System.Composition.Hosting.Core.CompositionOperation)
  at System.Composition.TypedParts.ActivationFeatures.DisposalFeature+<>c__DisplayClass0_0.<RewriteActivator>b__0 (System.Composition.Hosting.Core.LifetimeContext c, System.Composition.Hosting.Core.CompositionOperation o) [0x00000] in <9aac21a4a3f24063b2b8b59143acddfc>:0 
  at System.Composition.Hosting.Core.LifetimeContext.GetOrCreate (System.Int32 sharingId, System.Composition.Hosting.Core.CompositionOperation operation, System.Composition.Hosting.Core.CompositeActivator creator) [0x000a8] in <8e026c716fc84f38aae28085eaaee9fc>:0 
  at System.Composition.TypedParts.ActivationFeatures.LifetimeFeature+<>c__DisplayClass1_0.<RewriteActivator>b__0 (System.Composition.Hosting.Core.LifetimeContext c, System.Composition.Hosting.Core.CompositionOperation o) [0x00011] in <9aac21a4a3f24063b2b8b59143acddfc>:0 
  at System.Composition.Hosting.Core.CompositionOperation.Run (System.Composition.Hosting.Core.LifetimeContext outermostLifetimeContext, System.Composition.Hosting.Core.CompositeActivator compositionRootActivator) [0x0001c] in <8e026c716fc84f38aae28085eaaee9fc>:0 
  at System.Composition.Hosting.Core.LifetimeContext.TryGetExport (System.Composition.Hosting.Core.CompositionContract contract, System.Object& export) [0x0001d] in <8e026c716fc84f38aae28085eaaee9fc>:0 
  at System.Composition.Hosting.CompositionHost.TryGetExport (System.Composition.Hosting.Core.CompositionContract contract, System.Object& export) [0x00000] in <8e026c716fc84f38aae28085eaaee9fc>:0 
  at System.Composition.CompositionContext.GetExport (System.Composition.Hosting.Core.CompositionContract contract) [0x00000] in <12675e53c8854b48abd187539ce374db>:0 
  at System.Composition.CompositionContext.GetExport (System.Type exportType, System.String contractName) [0x00008] in <12675e53c8854b48abd187539ce374db>:0 
  at System.Composition.CompositionContext.GetExport[TExport] (System.String contractName) [0x00000] in <12675e53c8854b48abd187539ce374db>:0 
  at System.Composition.CompositionContext.GetExport[TExport] () [0x00000] in <12675e53c8854b48abd187539ce374db>:0 
  at OmniSharp.Stdio.Host.Initialize () [0x0000d] in <4fba2e716b9d446e8a7aaee8c0ec1500>:0 
  at OmniSharp.Stdio.Host..ctor (System.IO.TextReader input, OmniSharp.Stdio.Services.ISharedTextWriter writer, OmniSharp.IOmniSharpEnvironment environment, System.IServiceProvider serviceProvider, OmniSharp.CompositionHostBuilder compositionHostBuilder, Microsoft.Extensions.Logging.ILoggerFactory loggerFactory, System.Threading.CancellationTokenSource cancellationTokenSource) [0x00070] in <4fba2e716b9d446e8a7aaee8c0ec1500>:0 
  at OmniSharp.Stdio.Driver.Program+<>c__DisplayClass0_1.<Main>b__1 () [0x00138] in <f4fbf3b1468c4d85a1b6d592ea2ed3a2>:0 
  at OmniSharp.CommandLineApplication+<>c__DisplayClass11_0.<OnExecute>b__0 () [0x0000b] in <1029fd70a97546d4980c6c1d970ab776>:0 
  at McMaster.Extensions.CommandLineUtils.CommandLineApplication.Execute (System.String[] args) [0x00039] in <344a1e8cd6594b17b1e01f8df6ae8827>:0 
  at OmniSharp.CommandLineApplication.Execute (System.Collections.Generic.IEnumerable`1[T] args) [0x00042] in <1029fd70a97546d4980c6c1d970ab776>:0 
  at OmniSharp.Stdio.Driver.Program+<>c__DisplayClass0_0.<Main>b__0 () [0x00028] in <f4fbf3b1468c4d85a1b6d592ea2ed3a2>:0 
  at OmniSharp.HostHelpers.Start (System.Func`1[TResult] action) [0x0001c] in <1029fd70a97546d4980c6c1d970ab776>:0 

this is new to me, does the new Roslyn version now ship with an embedded SQLite?

[filipw]

OK I think Mono is no longer shipping SQLitePCLRaw.core in its GAC (I think it used to) so we should bundle it.
SQLite is a dependency of Microsoft.CodeAnalysis.Workspaces. I am not sure why it doesn't resolve now, looks like a packaging issue.
When I pull it from nuget and include in the artifact output folder, OmniSharp starts fine. Will include this in the PR then.