Add GitHub Actions pipeline for CMake build

[mcejp]

[EUA]

What is GitHub Actions for?

[buu342]

What is GitHub Actions for?

GitHub Actions is for Continuous Integration. Basically, every time you make a commit to the repository, GitHub will compile the project using a yaml script and make the compiled files downloadable to others via the Actions tab in the repository. This is nice since it means users don't need to download the source code and compile the project themselves in order to be on the most up-to-date executable.