feat(contentWrapperClass): Add feature and docs

[mattelen]

Closes #1914

FYI will release at a beta to test and make sure this works, before doing a minor version release

[Copilot]

Pull Request Overview

This PR adds a new contentWrapperClass prop to the Multiselect component that allows users to apply custom CSS classes to the dropdown content wrapper element, which is particularly useful when using the teleport feature to style the teleported dropdown element.

• Adds contentWrapperClass prop with support for String, Array, or Object types
• Updates component template to bind the new prop to the content wrapper element
• Adds documentation for the new prop in the Props component

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/Multiselect.vue	Adds contentWrapperClass prop definition and binds it to the content wrapper element
documentation/src/components/Props.vue	Documents the new contentWrapperClass prop in the props table

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[QuentiumYT]

Very interesting feature, I am wondering if we can have similar to that, an option to add additional classes to multiselect__tags? Would be a great way to customize with a library I use without overloading the CSS :)