Migrate from Travis to Github Actions

[lenacohen]

• Run automated tests on Github Actions to migrate off of Travis
• Chrome tests will fail on MV2 but (mostly) succeed on MV3 branch
  • 4-5 tests fail on MV3 branch, but they also fail locally, so this may be an issue separate from Github Actions
• The additions for Github Actions shouldn't impact our Travis testing, so we can wait to turn off Travis until we are confident in Github Actions

[ghostwords]

Thank you!!

[zoracon]

Amazing!