global_platform: make --install-parameters-* independently optional
gen_install_parameters() had contradictory logic: the outer guard required all three arguments to be non-None/non-empty (making them mutually inclusive), while the inner checks then treated each one as optional.
Make each parameter independently optional (defaulting to None) and remove the all-or-nothing guard from both the function and its caller. Simplify the function body to a straightforward single-pass construction of system_specific_params.
