Add support for async macro expansion

Author: roopekv

CodeGeneration/Sources/generate-swift-syntax/GenerateSwiftSyntax.swift

@@ -26,6 +26,9 @@ private let swiftParserGeneratedDir = ["SwiftParser", generatedDirName]
 privateletswiftParserDiagnosticsGeneratedDir=["SwiftParserDiagnostics", generatedDirName]
 privateletswiftSyntaxGeneratedDir=["SwiftSyntax", generatedDirName]
 privateletswiftSyntaxBuilderGeneratedDir=["SwiftSyntaxBuilder", generatedDirName]
+privateletswiftSyntaxMacroExpansionGeneratedDir=["SwiftSyntaxMacroExpansion", generatedDirName]
+privateletswiftSyntaxMacrosGenericTestSupportGeneratedDir=["SwiftSyntaxMacrosGenericTestSupport", generatedDirName]
+privateletswiftSyntaxMacrosTestSupportGeneratedDir=["SwiftSyntaxMacrosTestSupport", generatedDirName]
 privateletBASE_KIND_FILES:[SyntaxNodeKind:String]=[
 .decl:"SyntaxDeclNodes.swift",
 .expr:"SyntaxExprNodes.swift",
@@ -160,6 +163,28 @@ struct GenerateSwiftSyntax: AsyncParsableCommand{
  swiftSyntaxBuilderGeneratedDir +["RenamedChildrenBuilderCompatibility.swift"],
  renamedChildrenBuilderCompatibilityFile
 ),
+
+ // SwiftSyntaxMacroExpansion
+GeneratedFileSpec(
+ swiftSyntaxMacroExpansionGeneratedDir +["MacroExpansion.swift"],
+ macroExpansionFile
+),
+GeneratedFileSpec(
+ swiftSyntaxMacroExpansionGeneratedDir +["MacroSystem.swift"],
+ macroSystemFile
+),
+
+ // SwiftSyntaxMacrosGenericTestSupport
+GeneratedFileSpec(
+ swiftSyntaxMacrosGenericTestSupportGeneratedDir +["Assertions.swift"],
+ genericMacroAssertionsFile
+),
+
+ // SwiftSyntaxMacrosTestSupport
+GeneratedFileSpec(
+ swiftSyntaxMacrosTestSupportGeneratedDir +["Assertions.swift"],
+ macroAssertionsFile
+),
 ]
  // This split of letters produces files for the syntax nodes that have about equal size, which improves compile time