output-management: Add more detailed vrr configuration

[Drakulix]

wlr-output-configuration simply differentiates between enabled and disabled for adaptive sync. Given the flickering issues of some displays, we want to opportunistically enable VRR for fullscreen applications, so we need more state variants to represent all our vrr "modes".

Additionally wlr-output-configuration does not make an attempt to advertise if VRR is even available. This makes some sense as there really isn't any good feedback mechanism in the DRM api. The property used to enable VRR is simply a hint and may or may not be honored by the compositor: https://drmdb.emersion.fr/properties/3435973836/VRR_ENABLED

However we can at least check, that said variable is available and the connector advertises support https://drmdb.emersion.fr/properties/3233857728/vrr_capable. While the wlr-output-management allows the compositor to simply fail any configurations trying to enable VRR in these cases, we would like to hide the UI, so lets add an event to advertise availability.

[ids1024]

Seems reasonable. (As a protocol; I don't know much about how VRR works, but I presume the reasoning for this to exist is sound.) I guess it should document briefly how this interacts with zwlr_output_configuration_head_v1.set_adaptive_sync ?

Probably allow either, but calling both will produce an already_set error. (Looks like set_scale_1000 already documents that it works that way.)

[Drakulix]

I guess it should document briefly how this interacts with zwlr_output_configuration_head_v1.set_adaptive_sync ?

Probably allow either, but calling both will produce an already_set error. (Looks like set_scale_1000 already documents that it works that way.)

Good idea, added.