The open source OpenXR runtime

xrt: Add unique ID field to xrt_device master

Assign each device a unique 64-bit identifier for hash maps and caches. Synchronize the ID to IPC clients via device_get_info while keeping the existing uint32_t slot index for IPC lookups. Key the space overseer device map by the stable ID instead of the device pointer. Signed-off-by: Jakob Bornecrantz <tbornecrantz@nvidia.com> Part-of: <https://gitlab.freedesktop.org/monado/monado/-/merge_requests/2895>