Implement the Stimulus Standard Library

[tonysm]

The folks at the hotwired/stimulus-rails gem are experimenting with a Stimulus standard library. I think that's a neat idea and want to explore it here once it gets merged there.

[tonysm]

I've got an initial implementation here, but I'm gonna wait to see how the Rails version will play out.

One thing I'm not so sure about is that eager loading seems to work when registering controllers from multiple places:

eagerLoadControllersFrom("controllers", application)
eagerLoadControllersFrom("std", application)

But lazy-loading like below works, but triggers a console error (it tries to register all controllers twice, one for each call of the lazyLoadControllersFrom function:

lazyLoadControllersFrom("controllers", application)
lazyLoadControllersFrom("std", application)

The error I get is the following:

I have two controllers being used in that page: one called hello and another called toggle-class (took it from the Rails branch).

One idea I had was to try changing the stimulus-loading to take an array as for the "under" param, so we could implement this like:

lazyLoadControllersFrom(["controllers", "std"], application)

Which would only fail the controller registration if it fails for both "packages". Not sure.