feat: user-agent over gRPC

[dbolduc]

Fixes #1881

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.40%. Comparing base (ff49e5c) to head (873c28d).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2840      +/-   ##
==========================================
+ Coverage   95.39%   95.40%   +0.01%     
==========================================
  Files         101      102       +1     
  Lines        4274     4289      +15     
==========================================
+ Hits         4077     4092      +15     
  Misses        197      197              

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