JavaScript: More key APIs are now non-async

[knutwannheden]

Summary

This PR makes sync visitors the default in the TypeScript OpenRewrite implementation, with async visitors available as an alternative. This change improves performance by up to 20x for visitor traversals that don't require async operations.

Key API Changes

Visitor Base Classes

Before (Async Default)	After (Sync Default)	Async Alternative
TreeVisitor	TreeVisitor (sync)	AsyncTreeVisitor
JavaVisitor<P>	JavaVisitor<P> (sync)	AsyncJavaVisitor<P>
JavaScriptVisitor<P>	JavaScriptVisitor<P> (sync)	AsyncJavaScriptVisitor<P>
TypeVisitor<P>	TypeVisitor<P> (sync)	AsyncTypeVisitor<P>
JsonVisitor<P>	JsonVisitor<P> (sync)	AsyncJsonVisitor<P>
YamlVisitor<P>	YamlVisitor<P> (sync)	AsyncYamlVisitor<P>
PlainTextVisitor<P>	PlainTextVisitor<P> (sync)	AsyncPlainTextVisitor<P>
ParseErrorVisitor<P>	ParseErrorVisitor<P> (sync)	AsyncParseErrorVisitor<P>

TreePrinter API

• TreePrinter.print(): Now returns string directly (sync)
• TreePrinters.register(): Takes sync TreeVisitor<any, PrintOutputCapture> callback

Pattern & Template API

• Pattern.match(): Returns MatchResult | undefined (sync)
• Pattern.matchWithExplanation(): Returns MatchAttemptResult (sync)
• Template.apply(): Returns J | undefined (sync)
• PatternMatchingComparator.compare(): Returns boolean (sync)

Parser API

• Parser.parseOne(): Changed from Promise<SourceFile> to SourceFile (sync)
• All parsers now have sync parseOne(): JsonParser, YamlParser, PlainTextParser, JavaScriptParser

RPC Infrastructure

• RpcCodec.rpcSend(): Changed from Promise to void
• RpcSendQueue methods: All converted to sync (no more await needed)
• Sender visitors: JavaSender, TypeSender, JavaScriptSender, JsonSender, YamlSender now extend sync visitor base classes

Method Signatures

Visitor methods changed from:

protected async visitMethodDeclaration(method: J.MethodDeclaration, p: P): Promise<J | undefined>

To:

protected visitMethodDeclaration(method: J.MethodDeclaration, p: P): J | undefined

Collection Mapping

• Use mapSync() instead of mapAsync() for synchronous visitor operations
• mapAsync() still available for async visitors

Migration Guide

For code extending visitor base classes:

1. If your visitor needs async or for minimal work: Just change the visitor to extend AsyncXxxVisitor instead
2. If your visitor doesn't require async: Either change to extend AsyncXxxVisitor or proceed as in this example

Example migration to new sync visitor base class:

// Before
class MyVisitor extends JavaScriptVisitor<P> {
  override async visitMethodDeclaration(...): Promise<J | undefined> {
    // uses of `await` keyword and `mapAsync()`
  }
}

// After
class MyVisitor extends JavaScriptVisitor<P> {
  override visitMethodDeclaration(...): J | undefined {
    // removed uses of `await` keyword and use `mapSync()` instead
  }
}