Emote silent zone (#1342)

* Add an emote when the user is in silent zone

* Update silent icon strategy

* Update strategy for silent zone

 - Add svelte store
 - Show silent zone indication and replace camera

This update permit to hide silent zone when user is in Jitsi discussion

* Fix css silent zone

Signed-off-by: Gregoire Parant <g.parant@thecodingmachine.com>

front/src/Stores/MediaStore.ts

@@ -569,3 +569,8 @@ localStreamStore.subscribe((streamResult) => {
  * A store containing the real active media is mobile
  */
 export const obtainedMediaConstraintIsMobileStore = writable(false);
+
+/**
+ * A store containing if user is silent, so if he is in silent zone. This permit to show et hide camera of user
+ */
+export const isSilentStore = writable(false);