message: Add Jitsi auth check
  Checks for auth needed by looking up a well-known file from the preferred Jitsi domain. No file existing will assume no auth.
diff: @@ -34,6 +34,30 @@ export class Jitsi {
  return this.domain || 'jitsi.riot.im';
  }
  + /**
  + * Checks for auth needed by looking up a well-known file
  + *
  + * If the file does not exist, we assume no auth.
  + *
  + * See TODO add link
  + */
  + public async getJitsiAuth(): Promise<string|null> {
  + if (!this.preferredDomain) {
  + return null;
  + }
  + let data;
  + try {
  + const response = await fetch(`https://${this.preferredDomain}/.well-known/element/jitsi`);
  + data = await response.json();
  + } catch (error) {
  + return null;
  + }
  + if (data.auth) {
  + return data.auth;
  + }
  + return null;
  + }
  +
  public start() {
  const cli = MatrixClientPeg.get();
  cli.on("WellKnown.client", this.update);
  