feature(ClientUser): deprecate ClientUser#setGame in favour of ClientUser#setActivity (#2127)

* feature(ClientUser): backported ClientUser#setPresence

* fix ternary

* deprecation stuff

src/util/Constants.js

@@ -350,6 +350,21 @@ exports.Events = {
   DEBUG: 'debug',
 };
 
+/**
+ * The type of an activity of a users presence, e.g. `PLAYING`. Here are the available types:
+ * * PLAYING
+ * * STREAMING
+ * * LISTENING
+ * * WATCHING
+ * @typedef {string} ActivityType
+ */
+exports.ActivityTypes = [
+  'PLAYING',
+  'STREAMING',
+  'LISTENING',
+  'WATCHING',
+];
+
 /**
  * The type of a websocket message event, e.g. `MESSAGE_CREATE`. Here are the available events:
  * * READY