Publish Autosubmit 4.1.9 to DockerHub

Related to #1366, which has already been partially addressed with AS 4.1.9 published to PyPI. This issue is to update the Docker recipe, and to upload it to DockerHub.

@ltenorio did some useful improvements to our Dockerfile in !426.

@egarriga, for the previous image, 4.1.7, I used Luiggi's code, applying a patch manually and then publishing the image (we were in a hurry due to a deliverable in EDITO pending the new image, but that's still yuck).

This merge request contains the changes that Luiggi did, which are the AUTOSUBMIT_VERSION build argument, the conditional to handle that version or use a Git commit or install the latest version, and the change from dockerfiles to docker, as that's the name of the directory used in AS API & AS GUI (so that it's uniform across projects).

Cheers