Implement collapsible panels for the new room list (#32742)

* Add `react-resizable-panels` library

* Implement a custom SeparatorView

* Add a `LeftResizablePanelView`

* Add a custom `GroupView`

* Export everything from shared-components

* Make it possible to track width/collapse state through settings

* Add a view model to drive the views

* Render views without disrupting the old room list

* Fix lint error

* Disable user interaction on collapsed panel

* Prevent widgets fron hijacking pointer events

* Expand to full width on separator click

* Separator should be shown when focused via keyboard

* Update tests

* Use data-attribute for hover

* Write stories for SeperatorView

* Write vite tests for SeparatorView

* Write tests for LeftResizablePanelView

* More tests

* Fix lint errors

* Fix flakey border on the roomlst

* Fix storybook axe violation

* Update snapshots

* Fix playwright tests

* Fix sonarcloud issues

* Use translated string

* Add better js-doc comments

* Rename `ResizerSnapshot` to `ResizerViewSnapshot`

* Externalize react-resizable-panels

* Link figma designs to stories

* Write playwright tests

* Update screenshots

* Fix lint errors

* Update more screenshots

* Update more screenshots

* Fix flaky toast test

* Update apps/web/playwright/e2e/crypto/toasts.spec.ts

Co-authored-by: Andy Balaam <andy.balaam@matrix.org>

* Fix indentation

---------

Co-authored-by: Andy Balaam <andy.balaam@matrix.org>

apps/web/res/css/_common.pcss

@@ -54,6 +54,15 @@ Please see LICENSE files in the repository root for full details.
     isolation: isolate;
 }
 
+/**
+ * Disable pointer events inside the persistentElement container when the room-list is being resized.
+ * This is necessary to avoid the pointer events from being hijacked by the content rendered inside
+ * that div.
+ */
+:root:has(.mx_Separator[data-separator="active"]) #mx_PersistedElement_container {
+    pointer-events: none;
+}
+
 /**
  * We need to increase the specificity of the selector to override the
  * custom property set by the design tokens package