feat(role): add flags

[Earlopain]

Depends on #1334

https://discord.com/developers/docs/topics/permissions#role-object-role-flags

A better solution to what I was doing in my onboarding pr, wasn't documented at the time though. I also thought about adding the tags field as per #1316 but that has weird nullable types I didn't want to bother with. The issue should also be reopened as the PR doesn't address it fully and isn't merged.