2. Add site configuration overrides to theming/helpers.py
3. Move microsite.get_value from theming/helpers to site_configuration/helpers
4. Move microsite_configuration.microsite.get_value usages to site_configuration.helpers.values

These changes unify four different approaches to JWT creation, moving the core of the AccessTokenView to a general-purpose JwtBuilder class. This utility class defaults to using the system's JWT configuration, but it will allow overriding of the signing key and audience claim to support those clients which still require this. Part of ECOM-4566.

* Created URL route
* Expanded test code to confirm expected behavior

MA-2124

This will allow API servers to limit access based on scopes.

* mattdrayer: Remove individual JWT settings
* mattdrayer: Add settings defaults to JWT_AUTH calls

* mattdrayer: Remove individual JWT settings
* mattdrayer: Add settings defaults to JWT_AUTH calls

The JWT includes the user email and username, along with details pulled from the original access token (e.g. scope, expiration).

ECOM-4221

The JWT includes the user email and username, along with details pulled from the original access token (e.g. scope, expiration).

ECOM-4221

MA-2271
    Allow inactive users to authenticate.
MA-2273
    Provide custom authenticate method that allows users to provide email.

- Updated django-oauth2-provider libraries
- Added test ensuring issued access tokens have the basic scopes needed to get user info

ECOM-4197

Available backends:

* django-oauth-toolkit (DOT)
* django-oauth2-provider (DOP)

* Use provided client ID to select backend for
  * AccessToken requests
  * third party auth-token exchange
* Create adapters to isolate library-dependent functionality
* Handle django-oauth-toolkit tokens in edX DRF authenticator class

MA-1998
MA-2000