Add CSS cascade layers for Compound, shared components, and app/web styles (#33302)

* Layer Compound and shared component CSS

* Layer app theme CSS

* Remove !important flags from ActionBarView

* Remove unnecessary !important statements from shared components

* Avoid dead code errors for *.pcss just because layer is specified after @import url

* Remove unnecessary !important styling

* Override Banner defaults in RoomStatusBarView

* Updated snaps

* Updated snaps

* Fix styling of media body in app/web

* Fix styling for Compound anchors

* Fix styling issues in app/web

* More styling fixes

* Fix a problem extracting css for HTMLExport

* Revert changes

* Fix for theme styling

* Add test to improve coverage

* Prettier

* Fix styling issues

* Add data-kind attribute to avoid global styling override

* Update screenshot that now is correct

* Revert data-kind attribute

* Handle LinkPreview styling in .pcss

* Fix flaky test: Avoid racing the lazy-loaded ManageEventIndexDialog

* Take care of review comments

* Updated snaps

* Updated snaps again after merge

* Remove !important from RoomStatusBar

apps/web/test/unit-tests/components/structures/__snapshots__/RoomView-test.tsx.snap

@@ -237,7 +237,7 @@ exports[`RoomView for a local room in state ERROR should match the snapshot 1`]
           class="_content_n7ud0_38"
         >
           <p
-            class="_typography_6v6n8_153 _font-body-md-medium_6v6n8_60 _title_1xryk_24"
+            class="_typography_6v6n8_153 _font-body-md-medium_6v6n8_60 _title_mcq5y_24"
             id="_r_1cl_"
           >
             Could not start a chat with this user
@@ -247,7 +247,7 @@ exports[`RoomView for a local room in state ERROR should match the snapshot 1`]
           class="_actions_n7ud0_61"
         >
           <button
-            class="_button_1nw83_8 _primaryAction_1xryk_20 _has-icon_1nw83_60"
+            class="_button_1nw83_8 _primaryAction_mcq5y_20 _has-icon_1nw83_60"
             data-kind="primary"
             data-size="md"
             role="button"