Fixes to address scim-for-keycloak weirdness

[rhysyngsun]

What are the relevant tickets?

Part of https://github.com/mitodl/hq/issues/5561

Description (What does it do?)

This makes some tweaks to the SCIM adaptor to handle some weird data we're getting from the scim-for-keycloak plugin I didn't previously notice:

• The plugin is embedding JSON strings inside the JSON requests, which we have to parse because otherwise the data is being ignored.
• The was one edge case where we weren't handling emailOptIn.
• I had to switch over using displayName to using fullName. displayName worked on full data syncs, but if you only updated your full name on the account page it wasn't triggering a SCIM PATCH request over to Learn. There must be some special handling of it in the plugin, despite the appearance in the admin UI that you could use displayName for a custom user property.

How can this be tested?

• You'll need to update your SCIM Remote Provider User schema configuration by removing the custom attribute setting for displayName and adding a new attribute named fullName that uses the fullName custom attribute. All other settings can be left as the default.

You should be able to go through the following flows:

• Register as a new user:
  • Go to /realms/olapps/account/ on Keycloak, this redirects to the login pages and avoids us exercising the social auth code on Learn that can obfuscate whether SCIM worked correctly or not.
  • Create a new user, confirm your email. You should now be on the profile page.
  • Go to /admin on the Learn API and verify the user has been created and has the correct name and the email_optin setting is set to true/yes.
• Update an existing user:
  • Go to /realms/olapps/account/ on Keycloak and login as an existing user
  • Update combinations of the fields and confirm you see these updates propagate to Learn (e.g. test w/ updating all fields, test updating them individually, etc).