Preserve split UTF-8 request bodies in generated serializers

[Copilot]

Generated Blob, Queue, and Table serializers decoded request chunks independently before joining them, corrupting multi-byte UTF-8 characters split across stream boundaries.

• Serializer decoding
  • Collect request body chunks as Buffers.
  • Normalize string-emitted chunks with explicit UTF-8 encoding.
  • Decode only once after Buffer.concat(...).

segments.push(
  typeof buffer === "string"
    ? Buffer.from(buffer, "utf8")
    : Buffer.from(buffer)
);

resolve(Buffer.concat(segments).toString("utf8"));

• Regression coverage

  • Added shared generated-serializer tests for Blob, Queue, and Table.
  • Forces a multi-byte character to split across chunks and verifies deserialized JSON body text is preserved.

• Release notes

  • Added an Upcoming Release changelog entry for the request body decoding fix.

Original prompt

Fix Azure/Azurite issue #2670. The generated Blob, Queue, and Table readRequestIntoText helpers currently collect incoming Buffer chunks as strings and join them, which corrupts a multi-byte UTF-8 character split across chunk boundaries. Collect Buffer chunks, use Buffer.concat, then decode once as UTF-8 in all three serializers. Add focused regression tests that force a multi-byte character to split across chunks for Blob, Queue, and Table. Add an Upcoming Release ChangeLog entry. Run targeted tests, npm run build, npm run lint, formatting, and diff checks. Keep the change surgical. The locally validated version changed ChangeLog.md, src/{blob,queue,table}/generated/utils/serializer.ts, and tests/common/generatedSerializer.test.ts. Include 'Fixes #2670' in the PR body.

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🟡 Changes recommended

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🟡 Changes recommended

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[Copilot]

Copilot review overview

🟢 Approval recommended

No unresolved issues were identified, and the focused fixes, regression tests, and changelog update are included.

Review effort: Lite
Findings: None