Script to generate Dockerfiles by version + Github Action integration

I'm starting to think about a script to generate a Dockerfile for each Dogecoin Core release, and to have a way to update existing Dockerfiles/images when a template is edited, by using GitHub Action (GA) to automate Docker Hub tasks.
The goal here is to draft the script & the GA process.

The repository architecture would be the following, as defined in [the related issue](https://github.com/dogecoin/docker/issues/7#issuecomment-970673781):
```
.
└── version
├── distro1
│ └── Dockerfile
└── distro2
└── Dockerfile
└── version2
├── distro1
....
```
As I see it now, we can have 2 type of event :
| GitHub change | Docker Hub changes |
|--------------------|----------------------------|
| push on release | 1 version pushed, 1 image per distro |
| update of templates | all version updated, for all distros |

By reading GA documentation, I think it can be possible to achieve something like that :crossed_fingers:.

Should we update all Dockerfiles and images when a template is modified ? Docker Hub do not handle versioning for images, and changes can break related programs. Docker official images do not use a version strategy, but we may have change they don't.

I'm not sure how intensively GA should automate stuff. Do we try to do the publication of a new version with a workflow on Dogecoin Core called on releases ? Depend on the previous question, but do we automate update of templates (and Dockerfiles), GA propagating the change & committing automatically, or should do a PR ? Alternatively, do we let human run the script, creating locally new files & PR the result.

Any idea, expectation about the script/GA ? Any limitation to this current suggestion ?