checks: support GL and BB

[casperdcl]

• rename cml send-github-check -> cml send-check/check (Command naming consistency #762)
• Support GitLab equivalent(s)
  • https://docs.gitlab.com/ee/api/commits.html#post-the-build-status-to-a-commit
  • https://docs.gitlab.com/ee/ci/unit_test_reports.html <- requires modifying workflow (add art[ie]facts)
  • https://docs.gitlab.com/ee/ci/metrics_reports.html <- requires modifying workflow (add art[ie]facts)
  • https://docs.gitlab.com/ee/api/status_checks.html <-- ❤️
• Support Bitbucket equivalent(s)

[DavidGOrtega]

No, we tried and discussed this in the past.

https://docs.gitlab.com/ee/api/commits.html#post-the-build-status-to-a-commit is not like send-check as I reviewed in #830

About unit_tests and metrics:
They are not flexible having to generate a predefined format file as an artifact

[DavidGOrtega]

Also worth to watch https://docs.gitlab.com/ee/api/status_checks.html