feat: Require events.tsv for non-rest tasks

[effigies]

Promotes EVENTS_TSV_MISSING to an error.

This may end up with some false positives. We should be able to do some additional filtering based on path, but if the logic gets complicated then this would be a good use case for patching the schema.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 47.33%. Comparing base (8606dc5) to head (a9afbee).
Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3318   +/-   ##
=======================================
  Coverage   47.33%   47.33%           
=======================================
  Files         595      595           
  Lines       38031    38031           
  Branches     1261     1261           
=======================================
  Hits        18001    18001           
  Misses      19843    19843           
  Partials      187      187           

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