Superset API client to create custom roles

[shaidar]

Description/Context

Programmatically create custom Superset role definitions that we can use in conjunction with Moira groups to assign permissions to internal groups accessing the Superset UI.

Plan/Design

Using the following standard roles, create a few custom role definitions that some of our internal clients need for Superset UI access. Then, write a basic script to test out a forked Superset API client to create those new role definitions on our instance of Superset.

[shaidar]

Worked on the following:

• Refactored to allow the use of a token (obtained from Keycloak) to call the API instead of using a username and password as that doesn't work given our current config.
• Fixed ValueError: mutable default <enum 'FilterExpressionType'> for field expressionType is not allowed: use default_factory in different parts of the codebase.
• Fixed TypeError: Field.init() missing 1 required positional argument: 'kw_only'
• Tweaked superset_config.py to match the already created Superset Keycloak account to the preferred_username found in the JWT token and is tied to Keycloak's ol-superset-client