Automate build validation via github actions

[tylerbenson]

I intentionally submitted a PR but it was immediately closed: #1241

I think this change would be broadly useful to the community. Please let me know how I should proceed.

[miriamsr]

Thank you for opening this issue. At this time, we do not believe that all teams would benefit from build validation as not all students understand what GitHub Actions is. However, since many teams would benefit from learning about GitHub actions, this would be a great addition ftc-docs. I suggest creating a PR to add this documentation on the ftcdocs repo: https://github.com/FIRST-Tech-Challenge/ftcdocs