Combined Test Runner Github Action

[alterednode]

Is your feature request related to a problem? Please describe.
There are no automated tests.

Describe the solution you'd like
We should make a github action to automatically run tests for PRs and before releases, and block merging if they fail.
It would probably also be good to make them automatically run before release building?

[alterednode]

Whenever this is made, we should have multiple jobs on win / mac / linux(?) to find tests that could fail for os-specific reasons