[1/3] d3dx9: Add utility functions for loading files and resources into memory [try 3]

[Tony Wasserka]

- changed naming convention
- returning accurate error information now
- reduced functionality of load_resource_into_memory: we weren't sure on
IRC how to properly redirect D3DXGetImageInfoFromResourceA to the W
variant, so letting them FindResource and pass the result to the new
utility function is more appropriate IMO. Also, we don't fix the
functionality to RCDATA resources that way.