Add Optional User Approval

[Lermatroid]

Adds a option to enable user approvals.

• Can be enabled / disabled by config
• Users not able to access anything until approved and get shown a screen after registration saying awaiting approval
• Organizers can approve via admin dashboard

Discord request: https://discord.com/channels/1147243553467146321/1205867039965708308/1261026046090936350

[Lermatroid]

I'm introducing the `/i/*` directory for random interface pages like /i/approval. Other things could go here like the bug report page and such.