The previous approach with overriding `onload` no longer works if we use
indirect eval. However, since we now need to use a server anyways instead
of directly loading a file (because of Core), we can add a timeout to
the test server and implement this test in a cleaner way.
- add temporary function to Core for this POC
- add new CoreProcessor to access Keyman Core WASM
- add unit tests for new core processor
- add code to KeymanEngine and InputProcessor to load the new CoreProcessor
- add web server to manual tests and new action `start` to build script
This change requires the manual tests to be loaded from a web server
instead of loaded as file, because otherwise the wasm code won't be
loaded.
Currently we always load CoreProcessor. This should be improved in a future
change to only load when it is actually needed.
Part-of: #11293
