Support a list of assets in `Kino.JS` `:assets_path`

[jonatanklosko]

So it is easier to reuse files across kinos.

[aleDsz]

I have been thinking about that some days ago, where we could serve the assets from Kino and other users could create their SmartCells with these assets from kino

[jonatanklosko]

At some point we may have a some public css/js utilities, however I'm not sure that we should include them in each kino assets bundle. If we did that, the css/js would depend on the :kino version they use, so we would need to keep compatibility. So an appealing alternative would be to have a separate npm package with those assets, that would be versioned separately and that they could load from CDN, rather than each kino loading it on it's own.

So for now it's just so that assets can be shared between kinos in the same repository :)

[jonatanklosko]

For #289 we need assets to point to a single directory, so I would close this one.

I feel if we want better sharing long term it would make more sense to just use something like esbuild and simply bundle things as needed.