Include indication of whether the bot user is a member of the server in interaction payload

[Benricheson101]

Description

It would be useful if there was some indication of whether the bot user of an application is a member of the server an interaction is sent from. This would make it easier for applications to enable or disable certain actions that require a bot user in the server.

A possible solution would be to include a simple boolean of indicating if the bot user is a member, or including a nullable member object of the bot user in the server.

Alternatives Considered

One alternative is to make a request to a guild route when an interaction payload is received, and see if an error is returned. While this would work, it's a silly reason to make a request.