[Glitch] Add explanation to mute dialog, refactor and clean up mute/block UI

Port 9027bfff0c to glitch-soc

Signed-off-by: Thibaut Girka <thib@sitedethib.com>

app/javascript/flavours/glitch/features/ui/components/modal_root.js

@@ -15,6 +15,7 @@ import FocalPointModal from './focal_point_modal';
 import {
   OnboardingModal,
   MuteModal,
+  BlockModal,
   ReportModal,
   SettingsModal,
   EmbedModal,
@@ -32,6 +33,7 @@ const MODAL_COMPONENTS = {
   'DOODLE': () => Promise.resolve({ default: DoodleModal }),
   'CONFIRM': () => Promise.resolve({ default: ConfirmationModal }),
   'MUTE': MuteModal,
+  'BLOCK': BlockModal,
   'REPORT': ReportModal,
   'SETTINGS': SettingsModal,
   'ACTIONS': () => Promise.resolve({ default: ActionsModal }),