Add OAuth2 / OpenID Connect Authentication for Local Users and User/Role Based Read/Write Access

[hhund]

Wee should add support for OAuth2 / OpenID Connect based authentication for local users. Local users should be mapped to Practitioner and PractitionerRole resources.

This should allow us to allow specific users or users with specific roles to fill out QuestionnaireResponse resources. More generally we should implement a mechanism to specify read/write access for users and groups of users for all FHIR resources.