Add CI/CD to Github Actions for deployment

[asharonbaltazar]

To ensure quality pushes to master, there needs to be a CI/CD process, which is possible using Github Actions and Netlify (where the project is hosted).

• Frontend should use Netlify, which should give us a deployment link for every new PR.
• Functions should use Google's own CI/CD for Firebase Functions, which should give us a new deploy for every PR pertaining to /functions. We should also skip certain checks if they're not relevant to the code changes. /functions actions shouldn't run if the only changes in the PR pertain to the frontend.