feat: Add option to force pc to use turn relay candidates.

Helps with testing turn relay cases.

config.js

      disableNS
      enableTalkWhileMuted
      forceJVB121Ratio
+     forceTurnRelay
      hiddenDomain
      ignoreStartMuted
      */

package-lock.json

       }
     },
     "lib-jitsi-meet": {
-      "version": "github:jitsi/lib-jitsi-meet#ae45a0648f6a9acd562b253b212289fcb5bd6b05",
-      "from": "github:jitsi/lib-jitsi-meet#ae45a0648f6a9acd562b253b212289fcb5bd6b05",
+      "version": "github:jitsi/lib-jitsi-meet#a8dc3eaf104aa837f972d4ef60be95855c51a525",
+      "from": "github:jitsi/lib-jitsi-meet#a8dc3eaf104aa837f972d4ef60be95855c51a525",
       "requires": {
         "@jitsi/js-utils": "1.0.2",
         "@jitsi/sdp-interop": "1.0.3",

package.json

     "jquery-i18next": "1.2.1",
     "js-md5": "0.6.1",
     "jwt-decode": "2.2.0",
-    "lib-jitsi-meet": "github:jitsi/lib-jitsi-meet#ae45a0648f6a9acd562b253b212289fcb5bd6b05",
+    "lib-jitsi-meet": "github:jitsi/lib-jitsi-meet#a8dc3eaf104aa837f972d4ef60be95855c51a525",
     "libflacjs": "github:mmig/libflac.js#93d37e7f811f01cf7d8b6a603e38bd3c3810907d",
     "lodash": "4.17.19",
     "moment": "2.19.4",

react/features/base/config/configWhitelist.js

     'fileRecordingsEnabled',
     'firefox_fake_device',
     'forceJVB121Ratio',
+    'forceTurnRelay',
     'gatherStats',
     'googleApiApplicationClientID',
     'hideConferenceTimer',