Chore: Beta Dark Theme switch (#27324)

apps/meteor/client/sidebar/header/UserDropdown.tsx

apps/meteor/client/views/hooks/useExperimentalTheme.ts

apps/meteor/client/views/hooks/useThemeShortcut.ts

apps/meteor/client/views/root/AppLayout.tsx

apps/meteor/ee/server/services/package.json

apps/meteor/package.json

apps/meteor/packages/rocketchat-i18n/i18n/en.i18n.json

ee/apps/account-service/package.json

ee/apps/authorization-service/package.json

ee/apps/ddp-streamer/package.json

ee/apps/presence-service/package.json

ee/apps/stream-hub-service/package.json

ee/packages/ui-theming/package.json

ee/packages/ui-theming/src/PaletteStyleTag.tsx

ee/packages/ui-theming/src/palette.ts

ee/packages/ui-theming/src/paletteDark.ts

packages/core-typings/package.json

packages/fuselage-ui-kit/package.json

packages/gazzodown/package.json

packages/livechat/package.json