Implement more options for x509 CLI

[nhatnghiho]

Issues:

Resolves #CryptoAlg-3386

Description of changes:

Implement the following options for x509 cli command:

• extfile
• CA
• CAkey
• outform
• extensions
• pubkey

Call-outs:

I made several edits to the test utilities functions that involve comparing AWS-LC and OpenSSL's certificate outputs. These functions are moved to a centralized location to make the code look cleaner.

Testing:

Unit tests added, including missing coverage for some existing x509 options.

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.

[justsmth]

Would you rebase this onto the latest on main?

[github-actions]

clang-tidy made some suggestions

[codecov-commenter]

Codecov Report

❌ Patch coverage is 29.74576% with 829 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.64%. Comparing base (6d8caa7) to head (21f7808).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
tool-openssl/x509_test.cc	20.12%	512 Missing ⚠️
tool-openssl/test_util.cc	10.08%	209 Missing and 5 partials ⚠️
tool-openssl/x509.cc	73.89%	53 Missing ⚠️
tool-openssl/verify_test.cc	26.22%	45 Missing ⚠️
tool-openssl/req_test.cc	0.00%	3 Missing ⚠️
tool-openssl/rehash_test.cc	94.44%	0 Missing and 1 partial ⚠️
tool-openssl/test_util.h	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2735      +/-   ##
==========================================
- Coverage   78.93%   78.64%   -0.29%     
==========================================
  Files         677      678       +1     
  Lines      115525   116334     +809     
  Branches    16250    16302      +52     
==========================================
+ Hits        91187    91492     +305     
- Misses      23542    24053     +511     
+ Partials      796      789       -7     

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[justsmth]

There are a few failing in the X509 comparison tests: https://github.com/aws/aws-lc/actions/runs/18593051373/job/53012312901?pr=2735

[  FAILED  ] 4 tests, listed below:
[  FAILED  ] X509ComparisonTest.X509ToolCompareReqSignkeyDaysOpenSSL
[  FAILED  ] X509ComparisonTest.X509ToolCompareSignkeyOutformPEMOpenSSL
[  FAILED  ] X509ComparisonTest.X509ToolCompareSignkeyOutformDEROpenSSL
[  FAILED  ] X509ComparisonTest.X509ToolCompareReqCAOpenSSL

[github-actions]

clang-tidy made some suggestions