Impl SSL_client_hello_get1_extensions_present and friends

[justsmth]

Description of changes:

Implementation and documentation for:

• SSL_client_hello_get1_extensions_present
• SSL_client_hello_get_extension_order
• SSL_client_hello_get0_legacy_version

Testing:

Added new tests for coverage.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and the ISC license.

[github-actions]

clang-tidy made some suggestions

[codecov-commenter]

Codecov Report

❌ Patch coverage is 77.14286% with 32 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.69%. Comparing base (362e25e) to head (a6c2375).

Files with missing lines	Patch %	Lines
ssl/ssl_client_hello_test.cc	75.90%	19 Missing and 1 partial ⚠️
ssl/ssl_lib.cc	78.94%	12 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2561      +/-   ##
==========================================
- Coverage   78.70%   78.69%   -0.01%     
==========================================
  Files         645      645              
  Lines      110882   111023     +141     
  Branches    15671    15685      +14     
==========================================
+ Hits        87265    87375     +110     
- Misses      22929    22958      +29     
- Partials      688      690       +2     

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