Get user email from IUser

[Arzte]

Discord's API looks like it should return a user's email from /users/{id} through the user object it returns, but this method doesn't exist in discordie, so I'm opening this issue to get that in.

[abalabahaha]

It only returns an email if you're requesting /users/@me or making an OAuth-based request with identify+email scopes

[qeled]

Endpoint /users/:id has never returned emails and likely never will. You need to explicitly request OAuth permissions from the user to fetch it through /users/@me with an OAuth token as said above.

This is beyond the scope of this library.