ci: Build packages in update workflow

[Mrtenz]

After #3322, generating LavaMoat policies requires the build files to be present. Since the examples step requires build files as well, I've moved the build to a new job which is now a requirement for the other steps.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.06%. Comparing base (93a31e2) to head (0c15700).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3380   +/-   ##
=======================================
  Coverage   98.06%   98.06%           
=======================================
  Files         397      397           
  Lines       10929    10929           
  Branches     1720     1720           
=======================================
  Hits        10718    10718           
  Misses        211      211           

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