Merge with importmap module

Problem/Motivation

It looks like we had the same idea around the same time: https://www.drupal.org/project/importmap
(I think your module did not exist yet when I looked for existing implementations a few weeks ago.)

Proposed resolution

Your approach seems definitely cleaner.
I am totally OK with archiving my module and redirecting to yours, but they would need to have feature parity before doing this.

Remaining tasks

Here is what I think my module does that yours does not yet:

• A way to declare imports dynamically (something similar to hook_library_info_build)
• Support for scoped imports (scopes key in the importmap JSON)
• Invalidating browser cache when the JS files are upadted (similar to what core does)
• Optionally generate <link rel="modulepreload"> tags for modules in the importmap (this can help the browser parallelize requests, especially with long import chains)