Enabling new cudaconvertscale plugin

[Guillaume Denis]

Hello,

First of all, I am so happy to try the new release of GStreamer, thanks 
so much and congratulations!

I am building gstreamer 1.22 (from source on Debian 11) and currently 
when I "gst-inspect-1.0 nvcodec", 21 plugins are listed: in particular 
cudascale, cudaconvert and cudaconvertscale are missing.

I have a few questions if someone can help:

- is the only way to have them enabled to install the *whole* cuda 
(following https://developer.nvidia.com/cuda-downloads) or is it 
possible to install less dependencies?
- anyway I think these are runtime dependencies and don't need to be 
installed before building gstreamer 1.22?
- is there a CUDA version specification, or any between 11.7 or 12.0 
would work?

More generally, I am trying to understand if I could answer these 
questions by myself by inspecting files in 
https://gitlab.freedesktop.org/gstreamer/gstreamer/-/tree/main/subprojects/gst-plugins-bad/sys/nvcodec 
but I could not manage to do it... It could help for other plugins too.

If anyone is interested, I try to maintain a debian-based docker image 
that builds GStreamer:
https://github.com/ducksouplab/docker-gstreamer
(hoping to improve it with cudaconvertscale enabled of course!)

Thanks,
Guillaume