Adding a Shared folder:

* init some shared functions (videoHasWebchat, parseConfigUUIDs)
* api/room: checking that video has live enabled
* fix promise handling in initChat function
* removing some 'use strict' that are no more necessary in typescript

client/common-client-plugin.ts

@@ -1,6 +1,4 @@
 
-'use strict'
-
 function register ({ registerHook }: RegisterOptions): void {
   registerHook({
     target: 'action:router.navigation-end',