[Python] Support aws.protocoltests.json#JsonProtocol test model

[crisidev]

With this model I found 2 issues:

• Some union errors are generated with a string literal message that is not valid - [Python] Ensure we generate correct string literals in Python unions #2478
• Recursive shapes that are Box in Rust are not Pyclass - [Python] Support recursive shapes that are boxed in Rust #2476
• Code generation breaks with

Projection rest_json_validation failed: java.lang.IllegalStateException: The two inline modules have the same name but different attributes on them.
java.lang.IllegalStateException: The two inline modules have the same name but different attributes on them.
        at software.amazon.smithy.rust.codegen.server.smithy.InnerModule.findOrAddToList(RustCrateInlineModuleComposingWriter.kt:337)
        at software.amazon.smithy.rust.codegen.server.smithy.InnerModule.getWriter(RustCrateInlineModuleComposingWriter.kt:306)
        at software.amazon.smithy.rust.codegen.server.smithy.InnerModule.withInlineModule(RustCrateInlineModuleComposingWriter.kt:169)
        at software.amazon.smithy.rust.codegen.server.smithy.InnerModule.withInlineModuleHierarchy(RustCrateInlineModuleComposingWriter.kt:232)
        at software.amazon.smithy.rust.codegen.server.smithy.InnerModule.withInlineModuleHierarchy$default(RustCrateInlineModuleComposingWriter.kt:214)
        at software.amazon.smithy.rust.codegen.server.smithy.RustCrateInlineModuleComposingWriterKt$withModuleOrWithStructureBuilderModule$1.invoke(RustCrateInlineModuleComposingWriter.kt:67)
        at software.amazon.smithy.rust.codegen.server.smithy.RustCrateInlineModuleComposingWriterKt$withModuleOrWithStructureBuilderModule$1.invoke(RustCrateInlineModuleComposingWriter.kt:66)
        at software.amazon.smithy.rust.codegen.server.smithy.InnerModule$withInlineModuleHierarchyUsingCrate$4.invoke(RustCrateInlineModuleComposingWriter.kt:205)
        at software.amazon.smithy.rust.codegen.server.smithy.InnerModule$withInlineModuleHierarchyUsingCrate$4.invoke(RustCrateInlineModuleComposingWriter.kt:203)
        at software.amazon.smithy.rust.codegen.core.smithy.RustCrate.withModule$lambda$6(CodegenDelegator.kt:198)
        at software.amazon.smithy.codegen.core.WriterDelegator.useFileWriter(WriterDelegator.java:175)
        at software.amazon.smithy.rust.codegen.core.smithy.RustCrate.withModule(CodegenDelegator.kt:197)
        at software.amazon.smithy.rust.codegen.server.smithy.InnerModule.withInlineModuleHierarchyUsingCrate(RustCrateInlineModuleComposingWriter.kt:203)
        at software.amazon.smithy.rust.codegen.server.smithy.InnerModule.withInlineModuleHierarchyUsingCrate$default(RustCrateInlineModuleComposingWriter.kt:175)
        at software.amazon.smithy.rust.codegen.server.smithy.RustCrateInlineModuleComposingWriterKt.withModuleOrWithStructureBuilderModule(RustCrateInlineModuleComposingWriter.kt:66)
        at software.amazon.smithy.rust.codegen.server.smithy.ServerCodegenVisitor.stringShape(ServerCodegenVisitor.kt:521)
        at software.amazon.smithy.rust.codegen.server.python.smithy.PythonServerCodegenVisitor.stringShape(PythonServerCodegenVisitor.kt:180)
        at software.amazon.smithy.rust.codegen.server.python.smithy.PythonServerCodegenVisitor.stringShape(PythonServerCodegenVisitor.kt:59)
        at software.amazon.smithy.model.shapes.StringShape.accept(StringShape.java:41)
        at software.amazon.smithy.rust.codegen.server.smithy.ServerCodegenVisitor.execute(ServerCodegenVisitor.kt:250)
        at software.amazon.smithy.rust.codegen.server.python.smithy.RustServerCodegenPythonPlugin.execute(RustServerCodegenPythonPlugin.kt:63)
        at software.amazon.smithy.build.SmithyBuildImpl.applyPlugin(SmithyBuildImpl.java:357)
        at software.amazon.smithy.build.SmithyBuildImpl.applyProjection(SmithyBuildImpl.java:288)
        at software.amazon.smithy.build.SmithyBuildImpl.executeSerialProjection(SmithyBuildImpl.java:209)
        at software.amazon.smithy.build.SmithyBuildImpl.lambda$applyAllProjections$5(SmithyBuildImpl.java:182)
        at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183)
        at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1655)
        at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
        at java.base/java.util.stream.ForEachOps$ForEachTask.compute(ForEachOps.java:290)
        at java.base/java.util.concurrent.CountedCompleter.exec(CountedCompleter.java:746)
        at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
        at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020)
        at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656)
        at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594)
        at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183)