feat(git-node): verify tag signature during release promotion

[aduh95]

Before pushing the tag upstream, we can verify if it's signed with a known identity (name+email address+key combo), as the releaser might be relying on a mailmap entry, which are typically not used when verifying a tag signature (at least not by GitHub web UI).

/cc @nodejs/releasers

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.08%. Comparing base (e90258c) to head (924994c).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #879   +/-   ##
=======================================
  Coverage   80.08%   80.08%           
=======================================
  Files          39       39           
  Lines        4676     4676           
=======================================
  Hits         3745     3745           
  Misses        931      931           

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