Implement the member list with virtuoso (#29869)

* implement basic scrolling and keyboard navigation

* Update focus style and improve keyboard navigation

* lint

* Use avatar tootltip for the title rather than the whole button

It's more performant and feels less glitchy than the button tooltip moving around when you scroll.

* lint

* Add tooltip for invite buttons active state

As we have for other icon based buttons in the right panel/app

* Fix location of scrollToIndex and add useCallback

* Improve voiceover experience

- As well as stylng cells, set the tabIndex(roving)
- Natively focus the div with .focus() so screen reader actually moves over the cells
- improve labels and roles

* Fix jest tests

* Add aria index/counts and remove repeating "Open" string in label

* update snapshot

* Add the rest of the keyboard navigation and handle the case when the list looses focus.

* lint and update snapshot

* lint

* Only focus first/lastFocsed cell if focus.currentTarget is the overall list.

So it isn't erroneously called during onClick of an item.

* Put back overscan and fix formatting

* Extract ListView out of MemberList

* lint and fix e2e test

* Update screenshot

It looks like it is slightly better center aligned in the new list, as if maybe it was 1 px to high with the old one.

* Fix default overscan value and add ListView tests

* Just leave the avatar as it was

* We removed the tooltip that showed power level. Removing string.

* Use key rather than index to track focus.

* Remove overscan, fix typos, fix scrollToItem logic

* Use listbox role for member list and correct position/count values to account for the separator

* Fix inadvertant scrolling of the timeline when using pageUp/pageDown

* Always set the roving tab index regardless of whether we are actually focused.

Fixes the issue of not being able to shift+t

* Add aria-hidden to items within the option to avoid the SR calling it a group.

Also

* Make sure there is a roving tab set if the last one has been removed from the list.

* Update snapshot

yarn.lock

@@ -13091,6 +13091,11 @@ react-virtualized@^9.22.5:
     prop-types "^15.7.2"
     react-lifecycles-compat "^3.0.4"
 
+react-virtuoso@^4.12.6:
+  version "4.12.6"
+  resolved "https://registry.yarnpkg.com/react-virtuoso/-/react-virtuoso-4.12.6.tgz#20fe374d43cce3c9821e29f4cc4d050596d06d01"
+  integrity sha512-bfvS6aCL1ehXmq39KRiz/vxznGUbtA27I5I24TYCe1DhMf84O3aVNCIwrSjYQjkJGJGzY46ihdN8WkYlemuhMQ==
+
 "react@^16.8.0 || ^17.0.0 || ^18.0.0 || ^19.0.0", react@^19.0.0:
   version "19.1.0"
   resolved "https://registry.yarnpkg.com/react/-/react-19.1.0.tgz#926864b6c48da7627f004795d6cce50e90793b75"