Implement GuildBefore value in GuildUpdated event
Created by: Kiritsu
Summary
Implement GuildBefore value in GuildUpdated event.
Details / Changes proposed
If the guild is in the cache, we just copy it in a guild_old
variable that we pass in the event args. If the guild was not in the cache the before value will just be null.
Notes
I kept my tests in the test project.