Add docker publication to CI and remove uvicorn-only dockerfile and references

[emileten]

This PR:

• adds a publish-docker job to the CI github action. Inspired from the titiler-pgstac one, except that here we're only publishing the image based on the root gunicorn-uvicorn image.
• removes the uvicorn-only dockerfile and references to it, and renames the gunicorn+uvicorn based dockerfile to Dockerfile. We're only going to use this one.

As a reminder, docker build and push to ghcr will happen when :

• a new commit is pushed to main, in which case a docker image tagged latest is pushed
• a new tag is pushed, in which case a docker image with this tag is pushed
• a new release is published, in which case a docker image tagged with the corresponding github tag is pushed

[emileten]

@vincentsarago should we change the Dockerfile -- now we only have the one based on your gunicorn-uvicorn image -- so that it starts the app with uvicorn ?

[vincentsarago]

now we only have the one based on your gunicorn-uvicorn image -- so that it starts the app with uvicorn ?

I think it's fine as it is, people could just pass a CMD parameter to start uvicorn instead of Gunicorn