Website Discord integration

[Astraeus-]

Automatically update roles on Discord for captain status changes and registration as Free Agent.

Task list

• [x] Store our users Discord Id snowflakes in our database
• [x] Integrate storing users Discord Id snowflakes into registration flow
• [x] Update current user-base to include Discord Id snowflake
• [x] Complete Discord role assignment code
• [x] Integrate Discord role assignment code with current flows

[Fabian-Sommer]

Currently not working. Additional task: Assignment and disassignment of captain role should be in the sloth model, not in CreateTeam component