DM-45133: Set xtype on timestamp columns

[JeremyMcCormick]

• Add a validator to automatically set the votable_xtype to "timestamp" on Felis timestamp columns.

Checklist

• Ran Jenkins
• Added a release note for user-visible changes to docs/changes

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.91%. Comparing base (d239b8a) to head (f301416).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #117      +/-   ##
==========================================
+ Coverage   92.89%   92.91%   +0.01%     
==========================================
  Files          23       23              
  Lines        2884     2892       +8     
  Branches      290      291       +1     
==========================================
+ Hits         2679     2687       +8     
  Misses        118      118              
  Partials       87       87              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.