FFmpeg.AutoGen 8.0.0.1

Changes

• Fix: Remove postproc library dependency — FFmpeg 8.0 dropped it (fixes #334)
• Fix: Delegate return type byte* instead of string for const char* function pointers (fixes #271)
• Infra: Remove Git LFS, add FFmpeg download script (FFmpeg/download-ffmpeg.ps1)
• Infra: Branch reorganization (main is now the default branch)

NuGet Packages

• FFmpeg.AutoGen 8.0.0.1
• FFmpeg.AutoGen.Abstractions 8.0.0.1
• FFmpeg.AutoGen.Bindings.DynamicallyLinked 8.0.0.1
• FFmpeg.AutoGen.Bindings.DynamicallyLoaded 8.0.0.1
• FFmpeg.AutoGen.Bindings.StaticallyLinked 8.0.0.1