refactor: remove user bot methods (#2559)

* [WIP] Remove user bots

* more backend userbot removal

* Add mfaEnabled back

* revert client presences store removal

* partially revert getAuth changes

* remove more no longer used children of ClientUserGuildSettings

* fix a bug with this pr and TextBasedChannel.applyToClass

* remove a syncGuilds reference

* more user bot data handling

* various guildSync cleanup

* bots can't call logout

Had the user/bot portions of the code mixed up. Though, does this need to be a promise anymore?

* make ClientManager#destroy() sync

It nolonger needs to be a promise, and nothing depended on it being a promise that I can tell.

* requested change

* Fix massive error

* no longer used as it's userbot only

src/structures/Message.js

@@ -499,20 +499,6 @@ class Message extends Base {
     return this.channel.send(content, Object.assign(options, { reply: this.member || this.author }));
   }
 
-  /**
-   * Marks the message as read.
-   * <warn>This is only available when using a user account.</warn>
-   * @returns {Promise<Message>}
-   */
-  acknowledge() {
-    return this.client.api.channels(this.channel.id).messages(this.id).ack
-      .post({ data: { token: this.client.rest._ackToken } })
-      .then(res => {
-        if (res.token) this.client.rest._ackToken = res.token;
-        return this;
-      });
-  }
-
   /**
    * Fetches the webhook used to create this message.
    * @returns {Promise<?Webhook>}