Break out a separate mute modal with a hide-notifications checkbox.

app/javascript/mastodon/features/ui/components/modal_root.js

@@ -12,6 +12,7 @@ import BoostModal from './boost_modal';
 import ConfirmationModal from './confirmation_modal';
 import {
   OnboardingModal,
+  MuteModal,
   ReportModal,
   SettingsModal,
   EmbedModal,
@@ -23,6 +24,7 @@ const MODAL_COMPONENTS = {
   'VIDEO': () => Promise.resolve({ default: VideoModal }),
   'BOOST': () => Promise.resolve({ default: BoostModal }),
   'CONFIRM': () => Promise.resolve({ default: ConfirmationModal }),
+  'MUTE': MuteModal,
   'REPORT': ReportModal,
   'SETTINGS': SettingsModal,
   'ACTIONS': () => Promise.resolve({ default: ActionsModal }),