migrate existing users to new auth system

[okjodom]

No description provided.

[okjodom]

Did a successful dry run migration on the local database and came up with the following migration plan

Migration Plan:

• migrate chamas - chama service has a direct dependency on users for lookups like sending member invites. we should migrate this service before/in tandem with user migration
• communicate service maintenance
• lock down user registration
• snapshot and json dump current database with existing users
• normalize existing user data into new models and represenation
• use mongosh to bulk register normalized user data
• test user data access
• switch services over to migrated user db
• switch over app and auth to migrated user db

[okjodom]

blocked on #21