presentation-time: Add wp_refresh_cycle_info

Basically a continuation of !199 with some lessons learned.

• wp_presentation_feedback now carries information about the latching deadline
• the new wp_refresh_cycle_info now sends a sequence of events when the refresh cycle information changes
• wp_refresh_cycle_info is extensible with new events for VRR which will will likely need at some point
• informs about suspended refresh cycles
• makes it explicit when the refresh cycle duration is supposed to be constant
• makes discontinuities obvious

I also considered a request for retrieving a prediction for the next refresh cycle but I'll leave that for the future.