20220901-1: Reactions Update

This update adds support for message reactions, including the following REST routes:

• PUT /channels/<id>/messages/<id>/reactions/<emoji>: Add reaction to message
• DELETE /channels/<id>/messages/<id>/reactions/<emoji>: Remove reaction from message
• DELETE /channels/<id>/messages/<id>/reactions: Remove all reaction from a message

It adds a new permission React with value 536870912.

It adds three new events:

• MessageReact { id: String; channel_id: String; user_id: String; emoji_id: String; }
• MessageUnreact { id: String; channel_id: String; user_id: String; emoji_id: String; }
• MessageRemoveReaction { id: String; channel_id: String; emoji_id: String; }