XR_KHR_vulkan_enable2:
physicalDevice VkPhysicalDevice must match the device specified by xrGetVulkanGraphicsDevice2KHR
XR_KHR_vulkan_enable:
physicalDevice VkPhysicalDevice must match the device specified by xrGetVulkanGraphicsDeviceKHR
XR_KHR_vulkan_enable:
Add a trivial check that xrGetVulkanGraphicsDeviceKHR is called before xrCreateSession.
(our cached suggested device will be XR_NULL_HANDLE if it has not been called).
The XR_KHR_vulkan_enable2 code path already contains this check.
Abandons the assumption that in oxr_system.xdevs[], index 0 is HMD,
1 is left controller, 2 is right controller.
Now to represent the dynamically assigned roles, oxr_system.role contains
the index for a device in oxr_system.xdevs[] for head, left and right.
This role assignment happens on the client side and currently can not be updated
from the server side.
Also adds an enum that device drivers set indicating allowed assignments
(many controllers are physically designed to be held in a specific hand).
This also adds support for configurations with only a HMD and a right controller.
The previous two call helper macro copied the entire input struct to output struct.
In particular this did not keep the .type and .next fields intact.
Rather than trying to keep those intact, each struct type should have its own fill function,
only filling in the data we actually want to fill in.
This commits lays the foundation for actions in Monado (input and output).
There are lots of things missing and non-conformant in there. But once in
more people then just me can test it out and work on it.
This patch has been spun of the rather massive amount of work for adding input
devices into Monado. The interfaces feels somewhat stable now so could do
with another pair of eyes on them, before too much work is done on st/oxr.
