Hospital assignments

The goal is to associate manager user accounts with specific hospitals - more than one - rather than solely associating with ‘customer’ records.

More detail is at GBW-226 (and 240).

Core association will be in a user_site_role join table. Initially had considered just a user_site table, but with a role - defaulting to just the standard ‘manager’ role for now - will allow for expansion for users to have different roles at different hospitals, which has been a request in the past.

note

Correction: given that ‘roles’ are not actually stored in a database yet, we may hold off populating the ‘role’ field with anything at the moment.

Plan to add https://github.com/spatie/laravel-permission package and leverage that, but will need to convert current ‘role’ references to db ID things, which may take a bit of time…