Eliminate "configure_output()" and its long parameter list that has caused us
so much grief recently.
Replaced by a mutable version of for_each_output(), where you can observe
and modify fields of each DisplayConfigurationOutput directly.
This not only eliminates the coupling problem, but simplifies typical
display config changes that only touch a small number of fields (as
demonstrated in examples/*).
Validation checking that used to exist in some configure_output()
implementations has been reimplemented as common to all platforms now, and
moved to the Display::configure() stage.
Approved by PS Jenkins bot, Alberto Aguirre.