Changes

pySim/global_platform: replace deprecated argument group() creation

The global platform code used install_cap_parser.add_mutually_exclusive_group().add_argument_group()
But calling add_argument_group() on an exclusive group was never an intended feature nor
according to python docs was a working feature.

Change-Id: I4f73d3417a12b7fe94e33a265cdae244f3c9a1e9