A real-time hardware codec library for RustDesk based on FFmpeg

Codec

GPU	FFmpeg ram	FFmpeg vram	sdk vram
intel encode	qsv	qsv	Y
intel decode	d3d11	d3d11	Y
nvidia encode	nvenc(nv12->d3d11)	nvenc(d3d11)	Y
nvidia decode	d3d11	d3d11	N
amd encode	amf	amf	Y
amd decode	d3d11	d3d11	Y

The reason for discarding the codecs using Cucontext is discussed in the following forum thread: https://forums.developer.nvidia.com/t/cuctxdestroy-causing-system-freeze-and-black-screen/290542/1. Based on the information above, there are several optimizations and changes made to the codec:
- FFmpeg encoding AV_PIX_FMT_NV12 directly: The codec is modified to transfer AV_PIX_FMT_NV12 to AV_PIX_FMT_D3D11. This is done because FFmpeg doesn't use Cucontext if the device type is AV_HWDEVICE_TYPE_D3D11VA.
- FFmpeg decoding with AV_HWDEVICE_TYPE_CUDA acceleration: This functionality is disabled and replaced with AV_HWDEVICE_TYPE_D3D11VA. The decoding process now utilizes D3D11VA acceleration instead of CUDA.
- SDK decoding with CUDA acceleration: The CUDA acceleration support is disabled.
amd sdk remove h265 support, GPUOpen-LibrariesAndSDKs/AMF#432

vaapi: only tested on intel with va-driver-all, and hevc_vaapi encoding not supported on my pc
remove hevc_vaapi because of possible poor quality
amf: not tested, GPUOpen-LibrariesAndSDKs/AMF#378

FFmpeg ram encode
Y