chore: User to Organization Mapping

[cbolles]

• Store UserOrg model
• Have organization as request header
• Dedicated Organization Guard

Incomplete

• Have organization selection in UI

[mannyakosah]

maybe you wanna add a TODO comment of what the function "validate" is supposed to do?

[cbolles]

With the organization logic shifted, it is actually all it has to do now. It seems funky, but you'll see similar functionality in NestJS's official documentation. The validation is just for additional logic beyond the JWT validation.