[Build] Add Github workflows

[ktmud]

Recreating #9490 after some major refactoring.

CATEGORY

• Build / Development Environment

SUMMARY

Adding GitHub Actions per discussion in #9481 . This is a pure addition to the current build process for now. Nothing changed for Travis CI, except Cypress was upgraded from 3.6.1 to 4.3.0. We could evaluate whether to disable Travis CI once these GitHub Actions become more stable.

Jobs are split into 4 workflows to maximize parallelization:

• superset-backend.yml: python lint and unit tests
• superset-frontend.yml: frontend lint and unit tests
• superset-e2e.yml: end to end tests with Cypress
• license-check.yml: check license compatibility

A custom GitHub Action was created to generalize the building steps related to caching and dependencies.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

Once successfully integrated, GitHub PRs should have checks like below:

Meanwhile, use ktmud#27 to see these checks in action.

TEST PLAN

Make sure CI passes.

ADDITIONAL INFORMATION

N/A

REVIEWERS

@john-bodley @dpgaspar @craig-rueda @villebro