Add `/identify` command

[alfetopito]

Summary

• Add a bot command that takes as input a user id: /identify <user id>
• The result should be the full user details, if user is found on server
• It should be usable only by a given role. Let's call it moderators

Return would be something like:

   user: User {
     id: '0000000000',
     bot: false,
     system: false,
     flags: [UserFlags],
     username: 'namename',
     discriminator: '0000',
     avatar: '6b1020bf1b75d18c7eb0fc26a5788117',
     banner: undefined,
     accentColor: undefined
   }

Note

This is intended to be used in conjunction with a /nukebyavatar <avatar string> command or something similar.
Still not closed on the command name or the interface.
What matters is that the data returned here will be used by the input of another command