Update RazorSyntaxGenerator to reduce generated syntax code (#11806)

This change takes some updates from Roslyn's C# syntax generator tool to
greatly reduce the code system of the generated syntax files.

- Syntax.xml.Main.Generated.cs - Reduced from 1604 lines to 871 lines
- Syntax.xml.Syntax.Generated.cs - Reduced from 4128 lines to 2198 lines
- Syntax.xml.Internal.Generated.cs - Reduced from 5321 lines to 3822
lines

Author: DustinCampbell

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/Legacy/CSharpCodeParser.cs

@@ -2650,7 +2650,7 @@ private void ParseReservedDirective(SyntaxListBuilder<RazorSyntaxNode> builder,
         chunkGenerator = SpanChunkGenerator.Null;
         CompleteBlock();
         var keyword = OutputAsMetaCode(Output());
-        var directiveBody = SyntaxFactory.RazorDirectiveBody(keyword, cSharpCode: null);
+        var directiveBody = SyntaxFactory.RazorDirectiveBody(keyword, csharpCode: null);
 
         // transition could be null if we're already inside a code block.
         transition = transition ?? SyntaxFactory.CSharpTransition(SyntaxFactory.MissingToken(SyntaxKind.Transition), chunkGenerator: null);