[Feat] Shoundn't we have Docker images based on GDAL images?

[sbrunner]

Everything is in the title, with one question should we keep the actual images or replace them...

The goal is to have recent version of GDAL in this image.

And by the way also use Multistage build on Debian and Ubuntu images to have smaller image.

Describe alternatives you've considered
Don't use this image and build Grass in my own image.

[neteler]

Everything is in the title, with one question should we keep the actual images or replace them...

The goal is to have recent version of GDAL in this image.

Which image do you refer to?
Here the version matrix:

https://github.com/OSGeo/grass/blob/master/docker/README.md

And by the way also use Multistage build on Debian and Ubuntu images to have smaller image.

Yes, that would be very good - pull requests are welcome.