Draft: Add organization associations to User

What does this MR do and why?

Add owner_organization and organizations associations to User.

Add owned_users and users associations to Organization::Organization

How to set up and validate locally

1. Run the migrations
2. Associate an owner organization for a user by running:
   1. user = User.last
   2. user.owner_organization_id = 1
   3. user.save!
   4. user.reload.owner_organization.owned_users
3. Add organization_user and test the associations:
   1. organization_user = Organizations::OrganizationUser.new(organization_id: 1, user_id: <user-id>)
   2. organization_user.save!
   3. Organizations::Organization.find(1).users
   4. User.find(<user-id>).organizations

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #407837 (closed)