[dev]: separate unit and end-to-end testing #2646

In the future, we should consider separating the tests. We could have test:unit and test:e2e and then have separate jobs for each in ci.

When #2643 gets merged, running yarn test will only work if you have code-server running. Not ideal.

Instead, we should separate them and make it so both unit tests and e2e tests can be run locally and separately in ci.