Upgrade Generals and Zero Hour to x64

[xezon]

• Follow up for Get Generals and Zero Hour to compile with vs2022 & c++20 #471
• Follow up for Replace all inline assembler in Generals and Zero Hour #472

Upgrade Generals and Zero Hour to x64. It must not break the VS6 build and compatibility.

TODO:

• Zero Hour
• Zero Hour Tools
• Generals
• Generals Tools

[Mauller]

Requires moving to DX9 and 64bit versions of bink and miles or moving to alternatives

[PainnBot]

there is no 64bit versions of bink and miles and you have to use alternatives like OpenAL and ffmpeg, I'm currently already working on this and got nice progress so far just rewriting the Audio and Video libraries at the moment and fixing 2 remaining bugs caused by migrating from dx8 to dx9

[atraber]

I have a working Direct3D9 port in https://github.com/atraber/GeneralsGameCode/tree/d3d9-port in case that's useful.

A few weeks ago I started experimenting with adding modern graphics engine features like PBR-based shaders, bloom, shadow maps, etc. to see what graphical improvements this yield in Generals. So far with medium success. As part of that, I needed to port the engine to D3D9.

I think merging the D3D9 port is challenging. It's a change to the fundamental game engine of Generals. While everything works fine on my machine, it's difficult to verify that it works for everyone. Also consider that D3D9 breaks gentool support.
Another open question is if D3D8 compatibility should be kept (using different build targets, e.g.).

Let me know if you're interested in moving to D3D9. I'd be happy to contribute code and open PR.