Issue 4914/1: Move Output_property_engraver to Score level

Issue 4914/1: Move Output_property_engraver to Score level

This has the advantage of needing only one instantiation of the engraver
and not having \applyOutput mysteriously refrain from having an effect
in contexts without Output_property_engraver .

Due to the hierarchical nature of acknowledgers, acknowledgers in lower
contexts will now get to see the grobs before applyOutput has done its
work.  However, grobs are still unfinished (except for type, properties
initialized via context properties and cause) at the time they are
announced, with other details only getting filled in by the engraver
after announcement, so the potential for trouble seems low.
Acknowledgers should usually just register a grob (or write grob data)
with any actual reading of grob data occurring at the end of the
timestep instead or in the process-acknowledged phase.