Move SyntaxCollections from gyb to codegen

Author: kimdv

CodeGeneration/Sources/generate-swiftsyntax/GenerateSwiftSyntax.swift

@@ -57,6 +57,7 @@ struct GenerateSwiftSyntax: ParsableCommand {
       TemplateSpec(sourceFile: miscFile, module: swiftSyntaxDir, filename: "Misc.swift"),
       TemplateSpec(sourceFile: syntaxAnyVisitorFile, module: swiftSyntaxDir, filename: "SyntaxAnyVisitor.swift"),
       TemplateSpec(sourceFile: syntaxBaseNodesFile, module: swiftSyntaxDir, filename: "SyntaxBaseNodes.swift"),
+      TemplateSpec(sourceFile: syntaxCollectionsFile, module: swiftSyntaxDir, filename: "SyntaxCollections.swift"),
       TemplateSpec(sourceFile: syntaxEnumFile, module: swiftSyntaxDir, filename: "SyntaxEnum.swift"),
       TemplateSpec(sourceFile: syntaxKindFile, module: swiftSyntaxDir, filename: "SyntaxKind.swift"),
       TemplateSpec(sourceFile: syntaxTraitsFile, module: swiftSyntaxDir, filename: "SyntaxTraits.swift"),