Various compatibility bug fixes

Hi UX people!

This release fixes several bugs with the 2.9.0 release that caused problems when updating.

• More precisely initializing services/config for asset mapper by @weaverryan in #911
• [LiveComponent] Fix array valued checkboxes change event handling by @welcoMattic in #910
• [StimulusBundle] Marking only the AssetMapper integration as experimental by @weaverryan in #908
• [TwigComponent] Fix breaking (deprecation instead) when using .add() + StimulusBundle by @weaverryan in #914

Upgrading

Like with version 2.9.0, if you're upgrading from a 2.8 or earlier, you may get this error after running composer update:

Uncaught Exception: The service "chartjs.twig_extension" has a dependency on a non-existent service "stimulus.helper"

To fix this, run composer update one more time. The problem is, after the first update, Symfony Flex may not properly add StimulusBundle to config/bundles.php. After the 2nd update, it should be added, and the error will go away. See #907.

Diff: v2.9.0...v2.9.1

Cheers!