### 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.
Array modes;
	if (!openxr_api) {
		return modes;
	}
	uint32_t count = 0;
	const XrEnvironmentBlendMode *env_blend_modes = openxr_api->get_supported_environment_blend_modes(count);
	if (!env_blend_modes) {
		return modes;
	}
	for (uint32_t i = 0; i < count; i++) {
		switch (env_blend_modes[i]) {
			case XR_ENVIRONMENT_BLEND_MODE_OPAQUE:
				modes.push_back(XR_ENV_BLEND_MODE_OPAQUE);
				break;
			case XR_ENVIRONMENT_BLEND_MODE_ADDITIVE:
				modes.push_back(XR_ENV_BLEND_MODE_ADDITIVE);
				break;
			case XR_ENVIRONMENT_BLEND_MODE_ALPHA_BLEND:
				modes.push_back(XR_ENV_BLEND_MODE_ALPHA_BLEND);
				break;
			default:
				WARN_PRINT("Unsupported blend mode found: " + String::num_int64(int64_t(env_blend_modes[i])));
		}
	}
	return modes;
}
XRInterface::EnvironmentBlendMode OpenXRInterface::get_environment_blend_mode() const {