Provide docker images

[h-mayr]

The installation is currently complicated, mainly due to the ROOT dependency. If we would provide docker images, HDTV would be much more accessible. I think @YanzhaoW has already a pipeline for it. It would be very nice to have it in this repo for official releases.
Some additions on how to use the docker image should be made to the README.

[YanzhaoW]

Hi

Thanks for this issue. I could make a CD pipeline to automatically deploy a docker image to the dockerhub. But there are some open questions which we should discuss together:

1. What should be the version of hdtv that is used to create the docker image. Should it be the latest version of master or the release version (or even some stable releases)?
2. Which dockerhub account do we use to host docker images?
3. Should the images of the older versions be just overwritten and thrown away?

[op3]

1. I would suggest to provide images for every push to master, and then also provide tagged images for every release.
2. We could just use GHCR (GitHub container registry).
3. We should definitely keep releases. For simple commits to master, I think only keeping the latest one is sufficient (but I am not sure how easy it is to set that up).

[YanzhaoW]

Good ideas. I will get to work on this.