Dynamically read the resources endpoints from the `ResourceType` objects

[azmeuk]

Currently the resources endpoints are guessed from their names, but that would be nice to read them from ResourceType objects when provided.
The workflow could be:

• make a first request on /ResourceTypes to get all the ResourceType objects from the server
• pass them to the client object
• use the client as usual

This would require python-scim/scim2-models#6 to be implemented first.

[azmeuk]

Implemented in be0c26a