Add circleci config

[hoodmane]

I added some native tests (in nodejs) and browser tests, a server for the browser tests, a setup to webpack files for the browser tests, and circle ci config.

Result looks like this: The two browser-test failures are firefox due to a problem with the playwright docker image firefox installation. build-main fails because of typescript errors.

If merged, you will have to enable circleci in order to get it to actually work.