feat(release): support alpha releases

[RafaelGSS]

feat(release): support alpha releases

Node.js 27 introduces Alpha releases versioned as
vN.0.0-alpha.X.Y.Z (see nodejs/node#63135). Teach `git node release`
about them:

- --prepare detects alpha release lines from the NODE_ALPHA_*_VERSION
  macros in src/node_version.h, computes the next alpha version from
  the semver labels of the commits, and accepts
  --newVersion=N.0.0-alpha.X.Y.Z.
- When CHANGELOG_V{N}.md does not exist yet, --prepare creates it,
  updates the navigation of the other changelogs and the root
  CHANGELOG.md, and groups the commit list by semver-major, minor and
  patch.
- --newVersion=N.0.0 on an alpha release line prepares the first
  stable release, removing the alpha macros and relabelling Alpha
  entries as Current.
- --promote validates "(Alpha)" release commits, creates their GitHub
  releases as pre-releases, and, when promoting N.0.0, bumps main to
  N+1 with the alpha macros reset to 0.
- Fix the "Working on" commit corrupting node_version.h when the patch
  version goes from 9 to 10.

Refs: https://github.com/nodejs/Release/issues/1187

[codecov]

Codecov Report

❌ Patch coverage is 80.66038% with 82 lines in your changes missing coverage. Please review.
✅ Project coverage is 64.79%. Comparing base (ff0f558) to head (441278a).

Files with missing lines	Patch %	Lines
lib/prepare_release.js	82.15%	53 Missing ⚠️
lib/promote_release.js	52.45%	29 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1224      +/-   ##
==========================================
+ Coverage   64.50%   64.79%   +0.29%     
==========================================
  Files          65       66       +1     
  Lines       12300    13223     +923     
==========================================
+ Hits         7934     8568     +634     
- Misses       4366     4655     +289     

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