Zig API bindings for FFmpeg.

This does not build FFmpeg or implicitly link with any of its libraries. It's just the bindings.

First, update your build.zig.zon:

zig fetch --save git+https://github.com/myQwil/ffmpeg#v7.0.1-8

Next, add this snippet to your build.zig script:

const av = b.dependency("ffmpeg", .{}).module("av");
my_module.addImport("av", av);