`docker manifest ls` command to list manifest list draft from local storage

Description

Firstly, happy new year to everyone on this first day of 2024!

Getting to the point, whenever I attempt to push or delete a manifest list, I find it challenging to identify which manifest lists have already been created in local storage. While I know they are stored in the directory ~/.docker/manifests, the filenames in the directory are not human-readable. These names cannot guarantee a straightforward conversion to the correct manifest list name because the char / is replaced with underline _. When you attempt to reverse this conversion to obtain the manifest list name, you cannot be certain whether the underline _ should be replaced with / or left unchanged.

To implement the command manifest list, it is essential for the directory names stored in ~/.docker/manifests to be uniquely identifiable. So I decide to replace the char '/' with double underlines __ and the colon : with double dashs (--). Since image names are not allowed to contain double underlines or double dashs, this change does not impact other manifest subcommands.

In the end, I have successfully implemented the desired command locally, like this:

# docker manifest ls
REPOSITORY          TAG
example.com/first    1
example.com/second   2

# docker manifest ls -q
example.com/first:1
example.com/second:2

After using the docker manifest ls command, I can easily find the target manifest list to push or delete. It's very convenient！

I am willing to submit a PR, and it could be my first contribution to the Docker Cli project.

Start with the existing docker manifest subcommands and the local storage directory ~/.docker/manifests. Check how stored names are encoded and how push and delete locate them. Done means docker manifest ls lists locally stored manifest lists with repository and tag, while -q prints fully qualified names.