Move object-based script media assets to the public API

[Johannes Maron]

This is a successor to #29490 and a result of the discussion on #22298 and ​its corresponding forum thread.

This ticket aims to move object-based media assets to the public API and documentation.
A sample implementation has been part of the test suite for years, see also: ​https://github.com/django/django/blob/97a6a678c406b0049bd17bcd34f1d71d96141994/tests/forms_tests/tests/test_media.py#L717-L771

The goal is to support form assets with modern attributes, like:

<script type="module">
<!-- or -->
<script defer>
<!-- or -->
<script async>

And other standardized attributes, see ​https://developer.mozilla.org/en-US/docs/Web/HTML/Element/script

The same can be done for stylesheets via the link tag, which does support many more attributes than media, see also: ​https://developer.mozilla.org/en-US/docs/Web/HTML/Element/link

Considerations

We could deprecate "string" based assets. This may simplify django.forms since, the CSS grouping wouldn't be needed anymore.

[Sarah Boyce]

Accepting based off the forum discussion

[Sarah Boyce]

You cannot mark your own ticket as "Ready for checkin"

[Johannes Maron]

Sorry 🫣 I should know better