RAAML — Add STPA LossScenario stereotype

Currently the LossScenario is only defined in the STPA library and does not include a defining stereotype. The LossScenario is similar in purpose to the FMEAItem where it is typically the focus of a line item in an analysis table. The proposal is to add a LossScenario stereotype to the STPA Profile to be consistent with the FMEA and give a handle for table generation.

Introduce LossScenario Stereotype in STPA Profile

Add stereotype to be consistent with which stereotypes are defined for other methods. This is similar to FMEAItem Stereotype