add app info to workspace request - NOTE: depends on #320

[TessFerrandez]

PR for issue #306

What is being addressed

• User is required to add AAD app info to POST /workspaces for authentication
• App info is validated to ensure it exists and contains the right roles
• SP and role IDs are added to the workspace request to be used for user/workspace lookup

How is this addressed

• New class AccessService - this will act as an interface (abstract base class) for all AccessServices (if someone wants to change auth method)
• Implementation of AADAccessService that validates the auth_config (e.g. app - and returns relevant info to be stored in workspace request)
• POST Workspaces input takes auth_config which in the case of the AAD provider is app_id -- this is intentionally a dict so it can be different for different auth providers
• POST Workspaces calls validation/extraction - this class in turn picks the relevant AccessService based on the provider supplied
• Relevant tests updated
• Tests added for AccessService

NOTE: This PR depends on ENV VARS that will be added by @askew as part of #320

Closes #306

[github-actions]

Unit Test Results

  1 files    1 suites   2s ⏱️
59 tests 59 ✔️ 0 💤 0 ❌

Results for commit 4b39cb0.

♻️ This comment has been updated with latest results.

[tompaana]

Missing some documentation, but otherwise looks nice and clean!