feat: Enhance JSON serialization with improved orjson integration

[xingarr]

• Add robust error handling for orjson import and usage
• Implement comprehensive fallback mechanism when orjson is unavailable
• Add performance benchmarking utilities for JSON operations (mypy.json_bench)
• Include comprehensive test suite with 18 tests for edge cases
• Document performance characteristics and usage patterns
• Improve error handling for large integers exceeding 64-bit range
• Add detailed documentation explaining cache consistency requirements

This enhancement improves the faster-cache feature reliability and provides better visibility into JSON serialization performance, which is critical for mypy's incremental type checking caching mechanisms.

Resolves TODO items in mypy/util.py related to JSON optimization and sorted keys requirement documentation.

(Explain how this PR changes mypy.)

[github-actions]

According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅

[JukkaL]

We are moving from JSON serialization to a binary serialization format with a separate tool to convert binary cache files to JSON. The new format is currently enabled using --fixed-format-cache, but we are planning to make it the default (and eventually only) format within the next few releases. Unfortunately, it seems that this is not something that we need.

[hauntsaninja]

Thanks! This is a much larger diff than needed; if you are seeing an exception on load or dump, could you describe exactly what you are seeing? If so, open to a diff that only has the exception handling changes

[xingarr]

THanks for your review, so what you want me to update in this PR?