libhb: add cuda format filter.

[galad87]

Converts the frames to the pixel format required by the encoder. Should fix #5606
If someone with an NVIDIA GPU could test it.

Tested on:

• Windows 10+ (via MinGW)
• macOS 10.13+
• Ubuntu Linux

[sr55]

10Bit Source

NVEnc HEVC 10-bit
No Scaling: https://gist.github.com/sr55/228b827a3f7a7e722234eb47802e6996 (Hardware Decode)
Downscaling to 1080p https://gist.github.com/sr55/bdaf914b2dcf8fa2b703bf3923bdbba8 (Software Decode)

NVEnc HEVC 8-bit
No Scaling -> Encode Failed https://gist.github.com/sr55/2ea15bb200d08816f223f1a024d2ad3b (Software Decode)
Downcale to 1080p OK https://gist.github.com/sr55/72ddf243f54ecc39b67eeab1903f8832 (Software Decode)

[sr55]

8 Bit Source
8 -> 8 https://gist.github.com/sr55/9cd23c2579e545ba1fc8b8109d3375c1 (Hardware Decode)
8 -> 10 (Failed) https://gist.github.com/sr55/0b26f55e15eff89f9402653756d419cb (Software Decode)