Swap Admin4 multiselect plugin

[yubiuser]

What does this PR aim to accomplish?:

Swap the TOM Select plugin with https://github.com/davidstutz/bootstrap-multiselect which has better support for our "All"/"None"/"Apply" buttons.

Documentation at https://davidstutz.github.io/bootstrap-multiselect

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[rdwebdesign]

I tested the branch and it works and looks better then the other plugin.
I suggested a few changes to improve the colors (specially on the dark themes).

I also noticed a small issue, but I didn't debug it yet and I'm not 100% sure if this is caused by the plugin or something else.

Steps to reproduce:

• open the Select element (using mouse or Tab key).
• then use the Up or Down arrow keys
• the top dropdown menu will open.

EDIT:
I created a better video to show the issue.

[yubiuser]

This is an intersting bug. AI says

I’ve identified the likely root cause: once the multiselect menu is detached into body as a floating menu, arrow key events can bubble to Bootstrap’s global dropdown handler instead of staying scoped

[Copilot]

Pull request overview

This PR replaces the Admin UI’s group multi-select implementation based on Tom Select with bootstrap-multiselect to better support the custom “All” / “None” / “Apply” actions used in the groups tables.

Changes:

• Remove Tom Select vendor assets and dependency; add bootstrap-multiselect vendor assets and dependency.
• Rework utils.createGroupSelect() and group table scripts to initialize and control the new multiselect.
• Update CSS and page includes to load the new plugin and adjust the actions box styling/positioning.

Reviewed changes

Copilot reviewed 12 out of 19 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
vendor/tom-select/tom-select.complete.min.js	Removes Tom Select JS bundle from vendored assets.
vendor/tom-select/tom-select.bootstrap5.min.css.map	Removes Tom Select Bootstrap 5 sourcemap.
vendor/tom-select/tom-select.bootstrap5.min.css	Removes Tom Select Bootstrap 5 CSS.
vendor/bootstrap-multiselect/bootstrap-multiselect.min.js	Adds vendored Bootstrap Multiselect JS.
vendor/bootstrap-multiselect/bootstrap-multiselect.min.css	Adds vendored Bootstrap Multiselect CSS.
style/pi-hole.css	Renames actions box styles and adds positioning/visual overrides for the new dropdown.
scripts/lua/header.lp	Switches conditional plugin CSS include to Bootstrap Multiselect.
scripts/js/utils.js	Replaces Tom Select-based createGroupSelect() with a Bootstrap Multiselect-based implementation + wrapper.
scripts/js/groups-lists.js	Updates initialization and Apply-button wiring to use the new multiselect wrapper.
scripts/js/groups-domains.js	Updates initialization and Apply-button wiring to use the new multiselect wrapper.
scripts/js/groups-clients.js	Updates initialization and Apply-button wiring to use the new multiselect wrapper.
queries.lp	Replaces the Tom Select script include with Bootstrap Multiselect.
package.json	Adds bootstrap-multiselect dependency and removes tom-select.
package-lock.json	Locks bootstrap-multiselect and removes tom-select transitive entries.
groups.lp	Replaces Tom Select script include with Bootstrap Multiselect.
groups-lists.lp	Replaces Tom Select script include with Bootstrap Multiselect.
groups-domains.lp	Replaces Tom Select script include with Bootstrap Multiselect.
groups-clients.lp	Replaces Tom Select script include with Bootstrap Multiselect.

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[rdwebdesign]

AI says

I’ve identified the likely root cause: once the multiselect menu is detached into body as a floating menu, arrow key events can bubble to Bootstrap’s global dropdown handler instead of staying scoped

This is not really the issue.

The original select2 (used in the current master branch) also puts the .bootstrap-select element on the body:

but this issue never happened before. Something else is causing the issue with the other dropdown.