Update the web setup process

[josxha]

The package printing has a nice setup on web. Maybe it's possible to implement something similar.

maplibre-gl-js receives updates often. We don't want to release a new package version if upstream publishes bug fix releases and we don't want to include the big but often changing maplibre-gl-js as assets to avoid cluttering the repository. Therefore we should default to load from unpkg but provide documentation on how to load the library from app assets.

[josxha]

The benefit of reworking the web setup process is limited. It's more a "nice to have" than a necessity. If anyone finds a use case for this feature let me know and we can reopen.