Changes the prefix added in front of the jitsiRoomName

Previously, the prefix was computed using the org/world (in SAAS) or the instance part of public URLs.
Neither was guaranteeing the Jitsi Room would be unique accross rooms.
The new system computes a hash of the room URL and prepends it to the jitsi room name.

BREAKING CHANGE: this means the URL of the Jitsi room will change for all maps. Users having bookmarked the Jitsi room (for instance in the Jitsi mobile app) will need to update their bookmarks.

front/src/Connexion/Room.ts

@@ -18,7 +18,6 @@ export class Room {
     private _authenticationMandatory: boolean = DISABLE_ANONYMOUS;
     private _iframeAuthentication?: string = OPID_LOGIN_SCREEN_PROVIDER;
     private _mapUrl: string | undefined;
-    private _instance: string | undefined;
     private readonly _search: URLSearchParams;
     private _contactPage: string | undefined;
     private _group: string | null = null;
@@ -121,7 +120,6 @@ export class Room {
                 this._canReport = data.canReport ?? false;
                 this._loadingLogo = data.loadingLogo ?? undefined;
                 this._loginSceneLogo = data.loginSceneLogo ?? undefined;
-                this._instance = data.instance;
                 return new MapDetail(data.mapUrl);
             } else {
                 console.log(data);
@@ -200,13 +198,6 @@ export class Room {
         return this._group;
     }
 
-    get instance(): string {
-        if (!this._instance) {
-            throw new Error("Instance not fetched yet");
-        }
-        return this._instance;
-    }
-
     get expireOn(): Date | undefined {
         return this._expireOn;
     }