st/oxr: Add extension XR_FB_composition_layer_depth_test
Spec
According to the spec of XR_FB_composition_layer_depth_test, This extension enables depth-tested layer composition. The XrCompositionLayerDepthTestFB structure includes depth-test data which will be transported to runtime if layer wants to enable depth-test when composing.
Usage
Application adds XrCompositionLayerDepthTestFB
to the XrCompositionLayerBaseHeader::next
list and transfer to runtime client by xrEndFrame.