[uss_qualifier] Add potential generated actions selector conditions

[BenjaminPelletier]

This PR improves an aspect of #1810: to target selection of a specific ResourceEnvironmentsActionGenerator reliably (without regard to the placement of that action generator within the action structure), the test designer needs to be able to select instances that generate particular types of actions. This PR implements that ability. Tested to work by temporarily adding the parallelism rule below to f3548_self_contained and verifying that ConflictHigherPriority scenarios indeed ran sequentially while ConflictEqualPriorityNotPermitted scenarios continued to run in parallel.

        - max_parallelism: 1
          conditions:
            - is_action_generator:
                potentially_generates_any_of:
                  - test_scenario:
                      scenario_type: scenarios.astm.utm.ConflictHigherPriority