Migrate CI/CD to GitHub Actions

[mttrbrts]

As described in accordproject/technical-steering-committee#4

Please follow the conventions in https://github.com/accordproject/concerto/pull/236

• [x] Remove secrets from Travis (for AP maintainers: in Travis Repository Settings)
• [x] Disable Travis in the configuration (for AP maintainers: Travis Personal Profile > Settings > Accord Project
• [x] Remove .travis.yml and .travis directories in repo
• [x] Add .github/workflows directory based on those in ./concerto/.github/workflows
• [x] ~Remove scripts in ./scripts replace by those found in ./concerto/scripts~
• [x] Fix package.json notable adjustments: remove some of the old scripts, ~make sure code coverage works~
• [x] ~Test build on PR with timestamps~
• [x] ~Test build on GitHub release with version number~
• [x] Update GitHub "branch protection" rules to point to the new workflows instead of Travis

[Aniruddha-Shriwant]

@mttrbrts can I take this?

[jeromesimeon]

@mttrbrts can I take this?

Done and done! Your changes are now how we do CI in this repo. Thank you @Aniruddha-Shriwant for the great contribution (and being responding to requests for changes).