Scope and purpose

This PR upgrades the jQuery MultiSelect library, as part of the larger #3582 jQuery update.

The multiselect element has been updated quite a bit, and there is no longer a left-and-right layout. It is closer to a combobox or the select2 used for search in other parts of the application.

How to test

API Tokens

1. Open "User and API Administration" tool
2. Select "API Token List", and edit on any token.
3. Verify that there is a multiselect, and make changes.
4. Save the form, and verify that the changes were commited.

JWT

1. Open "User and API Administration" tool
2. Select "API Token List", and create a new token.
3. Verify that there is a multiselect, and make changes.
4. Save the form, and click "Back to token list"
5. Click on the name of the newly created token, and verify that the permissions you selected were added.

Screenshots

The library has changed the elements substantially, but the "After" uses the defaults from the library.

Before

After

Contributor Checklist

Every pull request should have this checklist filled out, no matter how small it is.
More information about contributing to NAV can be found in the
Hacker's guide to NAV.

• Added a changelog fragment for towncrier
• Added/amended tests for new/changed code
• Added/changed documentation
• Linted/formatted the code with ruff, easiest by using pre-commit
• Wrote the commit message so that the first line continues the sentence "If applied, this commit will ...", starts with a capital letter, does not end with punctuation and is 50 characters or less long. See https://cbea.ms/git-commit/
• Based this pull request on the correct upstream branch: For a patch/bugfix affecting the latest stable version, it should be based on that version's branch (<major>.<minor>.x). For a new feature or other additions, it should be based on master.
• If applicable: Created new issues if this PR does not fix the issue completely/there is further work to be done
• If it's not obvious from a linked issue, described how to interact with NAV in order for a reviewer to observe the effects of this change first-hand (commands, URLs, UI interactions)
• If this results in changes in the UI: Added screenshots of the before and after
• If this adds a new Python source code file: Added the boilerplate header to that file