Saved Scenario User Passthrough to myetm

[louispt1]

Description

In keeping with the 'single-point-of-entry' principle employed thus far in pyetm, we need to allow users to manage their saved scenarios via an etengine API endpoint that passes requests on to MyETM. That way users will be able to manage the roles set on saved scenarios via the Engine.

Ideal State

Users can perform CRUD operations in bulk on Saved Scenario Roles via the Engine API.

Proposed solution

• SavedScenarioUsersController with CRUD endpoints for bulk user operations