New theme ui in user settings (#12576)

* Add hook to get the theme

* Adapt subsection settings to new ui

* WIP new theme subsection

* Add theme selection

* Fix test types

* Disabled theme selector when system theme is used

* Update compound to `4.4.1`

* Add custom theme support

* Remove old ThemChoicePanel

* Fix QuickThemeSwitcher-test.tsx

* Fix AppearanceUserSettingsTab-test.tsx

* Update i18n

* Fix ThemeChoicePanel-test.tsx

* Update `@vector-im/compound-web`

* Small tweaks

* Fix CSS comments and use compound variable

* Remove custom theme title

* i18n: update

* test: add tests to theme selection

* test: update AppearanceUserSettingsTab-test snapshot

* test: rework custom theme

* playwright: fix audio-player.spec.ts

* playwright: appearance tab

* test: update snapshot

* playright: add custom theme

* i18n: use correct char for ellipsis

* a11y: add missing aria-label to delete button

* dialog: update close button tooltip

* theme: remove local state and handle custom delete

* theme: don't add twice the same custom theme

* test: update snapshot

* playwright: update snapshot

* custom theme: add background to custom theme list

* update compound web

* Use new destructive property on `IconButton` of theme panel

* test: update snapshots

* rename new ui into legacy

* remove wrong constructor doc

* fix theme selector padding

* theme selector: fix key

* test: fix e2e

playwright/e2e/audio-player/audio-player.spec.ts

@@ -160,7 +160,7 @@ test.describe("Audio player", () => {
 
         // Enable high contrast manually
         const settings = await app.settings.openUserSettings("Appearance");
-        await settings.getByTestId("mx_ThemeChoicePanel").getByText("Use high contrast").click();
+        await settings.getByRole("radio", { name: "High contrast" }).click();
 
         await app.closeDialog();