RLC: Remove NodeJS.ReadableStream from bytes request-body unions for browser-safe typings

[Copilot]

RLC currently emits NodeJS.ReadableStream in bytes request-body parameter unions, which breaks browser builds when @types/node is intentionally excluded (types: []). This change makes the emitted binary input type portable across browser and Node targets.

• Emitter typing update (RLC binary inputs)

  • Updated the shared binary request-body union in packages/typespec-ts/src/utils/modelUtils.ts:
    • from ... | NodeJS.ReadableStream
    • to ... | AsyncIterable<Uint8Array>
  • This preserves stream-based input support without requiring the NodeJS namespace in generated parameters.ts.

• Unit expectation updates

  • Updated RLC bytes generator assertions in packages/typespec-ts/test/unit/bytesGenerator.spec.ts to match the new emitted type.
  • Kept coverage focused on bytes request bodies and multipart bytes-related unions.

• Representative emitted type change

  // before
  body: string | Uint8Array | ReadableStream<Uint8Array> | NodeJS.ReadableStream;
  
  // after
  body: string | Uint8Array | ReadableStream<Uint8Array> | AsyncIterable<Uint8Array>;