[PJK]

Description

• The allocate-serialize-retry loop was ugly and inefficient, especially for large items that might take a number of tries to succeed
• Will also waste less memory
• The downside is that the old API doesn't match the new logic so well, the return value and the output parameter are redundant now. Given the number of clients (https://github.com/search?q=cbor_serialize_alloc&type=code), I will keep the function as-is for now since it is backwards compatible

Checklist

• I have read followed CONTRIBUTING.md
  • I have added tests
  • I have updated the documentation
  • I have updated the CHANGELOG
• Are there any breaking changes?
  • If yes: I have marked them in the CHANGELOG (example)
• Does this PR introduce any platform specific code?
• Security: Does this PR potentially affect security?
• Performance: Does this PR potentially affect performance?