### 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.
OpenXRDisplayRefreshRateExtension *drrext = OpenXRDisplayRefreshRateExtension::get_singleton();
	if (drrext) {
		return drrext->get_refresh_rate();
	}
	return 0.0;
}
void OpenXRAPI::set_display_refresh_rate(float p_refresh_rate) {
	OpenXRDisplayRefreshRateExtension *drrext = OpenXRDisplayRefreshRateExtension::get_singleton();
	if (drrext != nullptr) {
		drrext->set_refresh_rate(p_refresh_rate);
	}
}
Array OpenXRAPI::get_available_display_refresh_rates() const {
	OpenXRDisplayRefreshRateExtension *drrext = OpenXRDisplayRefreshRateExtension::get_singleton();
	if (drrext != nullptr) {
		return drrext->get_available_refresh_rates();
	}
	return Array();
}
double OpenXRAPI::get_render_target_size_multiplier() const {