presentation-time: Specify refresh bounds for VRR

When this extension was developed, we did not yet know how VRR hardware would behave in practice as it was not standardised, and the KMS interface was equally unstandardised.

Now things have shaken out to an acceptable level, we have a good idea of what we need, which is simply to include a base refresh rate - the rate the compositor would drive the display for non-VRR clients - as well as upper and lower bounds on the refresh rate for VRR clients.

Bump the protocol to version 2 to include a new event specifying the bounds, as well as a new flag bit for presentations on VRR outputs. Since the presented event is a destructor, the new event will be sent before presented.

Signed-off-by: Daniel Stone daniels@collabora.com