Create GitHub actions to test any code before merging

### Background on the problem the feature will solve/improved user experience
Add GitHub Actions to test and build new code pushed to a branch or committed to a pull request. Code that passes all the steps in the GitHub action can be merged in the repository.

### Describe the solution you'd like
A GitHub action runs whenever code is committed to any branch or PR is made to the main branch for each of the following components:
- [ ] website folder
- [ ] mobile folder
- [ ] backend folder

Refer to a similar action that was implemented for the[ UI folder in Five Fifths Voter project.](https://github.com/Call-for-Code-for-Racial-Justice/Five-Fifths-Voter/issues/232)

Each action will
- [ ] install dependencies
- [ ] build for production
- [ ] run all tests
- [ ] linting with [prettier](https://prettier.io/docs/en/index.html). Discuss with the team on what linter to use.

### Tasks
- [ ] Ensure install, build and lint steps run locally on your system
- [ ] Read more about [GitHub actions](https://docs.github.com/en/actions/learn-github-actions)
- [ ] Create an action for each folder. You can read more [JavaScript build actions here](https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-nodejs-or-python).
- [ ] Commit and push your GitHub action code.
- [ ] Go to the [Actions tab](https://github.com/Call-for-Code-for-Racial-Justice/FairChange/actions) to see if it worked.

### Acceptance Criteria
GitHub action runs for every new code commit and PR.

FYI @demilolu

Beginne damit zu prüfen, wie die Ordner für Website, Mobile und Backend lokal Abhängigkeiten installieren, bauen, testen und linten. Vergleiche die verlinkte Five Fifths Voter UI action und lies die Dokumentation zu GitHub Actions, bevor du für jeden Ordner eine action erstellst. Als erledigt gilt die Aufgabe, wenn die actions bei neuen Commits und Pull Requests ausgeführt werden und die angeforderten Schritte erfolgreich abschließen.

Vom Indexierungsmodell aus dem Issue-Text verfasst.