`container image tree` command for showing image parentage.

[dev-kvt]

It would be useful to have a command like:

container image tree

Instead of showing a flat list of images, it could display parent-child relationships.

Example:

ubuntu:24.04
├── python:3.12
│   ├── my-api
│   └── worker
└── node:22
    └── frontend

When you have many locally built images, container image ls becomes hard to navigate. A tree view would make it much easier to understand which images are based on others and help with cleanup and debugging. It could also optionally show image sizes with a --size flag.

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[dev-kvt]

#2005
This PR introduces the container image tree subcommand. Previously, when dealing with many locally built images, container image ls produced a flat list that became difficult to navigate and clean up.

This new command dynamically calculates image dependencies by inspecting layer architecture (rootfs.diffIDs) and displays the images in a visual parent-child hierarchy. It seamlessly matches variants across different architectures, and includes a --size flag to display human-readable byte counts alongside the tree.