venus: implement VK_ANDROID_external_memory_android_hardware_buffer (part 2/2)

This completes the AHB extension implementation for venus and passes the entire cts, although there're some bits left:

1. size returned from vn_GetAndroidHardwareBufferPropertiesANDROID might be better retrieved from the memory requirement by creating an image there temporarily.
2. need to fix the multi-planar format support

For quick reference: part 1 is here: !10847 (merged)

/cc @olv