refactor: move Guild#defaultRole to RoleStore#everyone (#3347)

* remove guild#defaultRole

* add RoleStore#defaultRole

* typings

* fix trailing space

* another one

* Rename it to everyone

src/structures/Guild.js

@@ -489,15 +489,6 @@ class Guild extends Base {
     return this.client.channels.get(this.embedChannelID) || null;
   }
 
-  /**
-   * The `@everyone` role of the guild
-   * @type {?Role}
-   * @readonly
-   */
-  get defaultRole() {
-    return this.roles.get(this.id) || null;
-  }
-
   /**
    * The client user as a GuildMember of this guild
    * @type {?GuildMember}