feat: add support for Immutable dictionaries

[TimothyMakkison]

Resolve the last two types from #250

• Added support for ImmutableDictionary and ImmutableSortedDictionary
• Added guards to DictionaryMappingBuilder to prevent existing immutable types from being assigned to in a foreach loop. - I did not copy the approach of checking for a implicit setter from the Immutable Enumerable types as this would conflict with fix: Insert a cast to IDictionary when an explicit setter is present #341.
• Added tests.

[codecov-commenter]

Codecov Report

Merging #351 (76ae6aa) into main (dce4b42) will increase coverage by 0.37%.
The diff coverage is 92.54%.

❗ Current head 76ae6aa differs from pull request most recent head 6fed80e. Consider uploading reports for the commit 6fed80e to get more accurate results

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@@            Coverage Diff             @@
##             main     #351      +/-   ##
==========================================
+ Coverage   91.71%   92.08%   +0.37%     
==========================================
  Files         109      122      +13     
  Lines        3379     3866     +487     
  Branches      438      526      +88     
==========================================
+ Hits         3099     3560     +461     
- Misses        189      207      +18     
- Partials       91       99       +8     

Impacted Files	Coverage Δ
src/Riok.Mapperly.Abstractions/MapEnumAttribute.cs	100.00% <ø> (ø)
...berMappings/MemberNullDelegateAssignmentMapping.cs	57.14% <0.00%> (ø)
.../Mappings/NewInstanceObjectFactoryMemberMapping.cs	100.00% <ø> (ø)
...Mapperly/Descriptors/UserMethodMappingExtractor.cs	98.38% <50.00%> (ø)
...riptors/MappingBuilders/QueryableMappingBuilder.cs	68.42% <68.42%> (ø)
...Descriptors/Mappings/EnumFromStringParseMapping.cs	73.68% <73.68%> (ø)
...ptors/Mappings/MemberMappings/NullMemberMapping.cs	76.27% <76.27%> (ø)
src/Riok.Mapperly/Symbols/FieldMember.cs	78.57% <78.57%> (ø)
src/Riok.Mapperly/Symbols/PropertyMember.cs	78.57% <78.57%> (ø)
...lders/NewInstanceObjectMemberMappingBodyBuilder.cs	80.17% <80.17%> (ø)
... and 59 more

... and 1 file with indirect coverage changes

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[latonz]

Thank you for the updates!
Sorry for the late feedback. 2-3 smaller points to discuss / fix, otherwise it looks really good to me 😊
Could you then also rebase (I think there may be some conflicts 🤔) and squash into one feature commit? Thanks!

[github-actions]

🎉 This PR is included in version 2.8.0-next.2 🎉

The release is available on:

• GitHub release
• v2.8.0-next.2

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