emoji icons for build jobs

Someone wanted to have ⚠ sign on manual deploy jobs to indicate they should be pressed with care.

So, i added unicode symbol to job name:

⚠deploy:dvideo.test.local⚠:
  <<: *deploy
  environment: test/dvideo.test

it looks a bit poor, and i was thinking maybe having structured support for such is more useful:

deploy:dvideo.test:
  <<: *deploy
  icon: warning
  environment: test/dvideo.test

this way it could be perhaps better shown in views, perhaps not show with small icons etc. also having ascii in .yml makes it more readable.