This MR contains a set of patches that move away from using `D3DFORMAT` inside of `struct d3dx_image`. This will allow us to support formats that do not have a direct mapping to `D3DFORMAT`, and eventually once we share code with d3dx10/d3dx11 formats that do not have a direct mapping to `DXGI_FORMAT`.
I've pushed a branch [here](https://gitlab.winehq.org/cmcadams/wine/-/tree/UPSTREAM/d3dx9-new-fmt-id-v1?...) containing patches that actually use this new internal format system in practice. I would've included those in this MR, but that seemed like it'd make for a rather large MR. Hopefully splitting it this way makes it easier to review. :)
-- v2: d3dx9: Use the d3dx_pixel_format_id enumeration inside of the WIC pixel format lookup structure. d3dx9: Use the d3dx_pixel_format_id enumeration inside of the DDS pixel format lookup structure.