Simplify assets.yaml

[tilgovi]

I think we should be able to simplify the assets by removing all the stuff that's in the h package's assets.yaml and only overriding the ones we want to change.

So all the vendor libs can be removed from the assets.yaml in this repo.

We only should be specifying app_js, app_css, auth_js, auth_css, inject_js, and inject_css in the assets.yaml here. These should use the built assets from h, "hypothesis.js", "hypothesis.css", etc. Let's not worry about minification for the moment. The auth stuff should be blank, because we're developing that in tree here and then using those assets instead of the upstream ones.

Then we can add a webassets.bundles list (space separated, overrides later in the line) to the .ini files to load both assets files.

The only snag is that I forgot to add asset spec support for the bundles directive in pyramid_webassets, so we can't say "h:assets.yaml" or anything like that. But we should copy it over verbatim and do our overrides in a separate file, rather than trying to merge changes between them.

[tilgovi]

We'll also have to list the vendor libs maintained in tree.

The ones with the h:scripts/plugin/{bridge,discovery,heatmap,threading,toolbar}.js contents.

[tilgovi]

Turns out we do have asset spec support for webassets.bundles. It's all good now.