Add cosmos validate to check plugins

[jmthomas]

closes #1337

[codecov[bot]]

Codecov Report

Merging #1675 (e0f5104) into master (b475170) will increase coverage by 7.70%. The diff coverage is n/a.

:exclamation: Current head e0f5104 differs from pull request most recent head a4350a4. Consider uploading reports for the commit a4350a4 to get more accurate results

@@            Coverage Diff             @@
##           master    #1675      +/-   ##
==========================================
+ Coverage   70.67%   78.37%   +7.70%     
==========================================
  Files          27      207     +180     
  Lines        1272    16924   +15652     
==========================================
+ Hits          899    13265   +12366     
- Misses        373     3659    +3286     

Impacted Files	Coverage Δ
app/controllers/completed_script_controller.rb
config/initializers/process_manager.rb
app/channels/application_cable/channel.rb
config/initializers/cors.rb
app/channels/application_cable/connection.rb
config/application.rb
config/initializers/cts.rb
config/environment.rb
app/controllers/application_controller.rb
app/controllers/reaction_controller.rb
... and 224 more

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