Support Rail's importmap

[vietqhoang]

Is there an existing issue for this?

• [X] I have searched the existing issues

Feature description

Currently there is no package ecosystem support for importmap-rails.

I have searched importmap both in the Issues and Pull requests, with no result returned.

• https://github.com/dependabot/dependabot-core/pulls?q=is%3Apr+importmap
• https://github.com/dependabot/dependabot-core/issues?q=is%3Aissue+importmap

There has been discussion in importmap-rails about addressing outdated pins, which led to this result.

It would be great for the Ruby on Rails community to have dependabot support for importmap.