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

Inizia verificando come le cartelle website, mobile e backend installano le dipendenze, eseguono la build, i test e il linting in locale. Confronta l’action collegata di Five Fifths Voter UI e consulta la documentazione di GitHub Actions prima di creare un’action per ogni cartella. Il lavoro è completato quando le action vengono eseguite per i nuovi commit e le pull request e completano correttamente i passaggi richiesti.

Scritto dal modello di indicizzazione a partire dal testo della issue.