### Godot version

4.2.dev 80de898d721f952dac0b102d48bb73d6b02ee1e8

### System information

OpenXR

### Issue description

The Godot 3 OpenXR plugin supported obtaining boundary/guardian information in order to obtain play space logic. While we do have a function in the `XRInterface` in Godot 4 that is supposed to retrieve this information (`get_play_area`) it is not implemented on the Godot 4 `OpenXRInterface`.

This logic needs to be ported.

### Steps to reproduce

Call `get_play_area`, be amazed by it not returning data :P

### Minimal reproduction project

Any XR project.
case XR_TYPE_EVENT_DATA_INSTANCE_LOSS_PENDING: {
				XrEventDataInstanceLossPending *event = (XrEventDataInstanceLossPending *)&runtimeEvent;
				
				
				print_verbose(String("OpenXR EVENT: instance loss pending at ") + itos(event->lossTime));
				return false;
			} break;
			case XR_TYPE_EVENT_DATA_SESSION_STATE_CHANGED: {
				XrEventDataSessionStateChanged *event = (XrEventDataSessionStateChanged *)&runtimeEvent;
				session_state = event->state;
				if (session_state >= XR_SESSION_STATE_MAX_ENUM) {
					print_verbose(String("OpenXR EVENT: session state changed to UNKNOWN - ") + itos(session_state));
				} else {
					print_verbose(String("OpenXR EVENT: session state changed to ") + OpenXRUtil::get_session_state_name(session_state));
					switch (session_state) {
						case XR_SESSION_STATE_IDLE:
							on_state_idle();
							break;
						case XR_SESSION_STATE_READY:
							on_state_ready();
							break;
						case XR_SESSION_STATE_SYNCHRONIZED:
							on_state_synchronized();
							break;
						case XR_SESSION_STATE_VISIBLE:
							on_state_visible();
							break;
						case XR_SESSION_STATE_FOCUSED:
							on_state_focused();
							break;