CI/CD improvements

[azkrishpy]

Issue #, if available:

N/A

Description of changes:

Adds CI/CD workflows mirroring awslabs/aws-c-common#1250:

• check-abi.yml — ABI compliance check on PRs
• release.yml — manual (workflow_dispatch) release with auto version bump + tag
• block-needs-review.yml — gate merges labeled needs-review
• VERSION file seeded from latest release tag
• CMakeLists.txt: derive target VERSION from VERSION file via aws_get_version()

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

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.11%. Comparing base (0c26c42) to head (b9d88c0).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #666      +/-   ##
==========================================
- Coverage   89.14%   89.11%   -0.03%     
==========================================
  Files          23       23              
  Lines        8044     8160     +116     
==========================================
+ Hits         7171     7272     +101     
- Misses        873      888      +15     

see 1 file with indirect coverage changes

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