feat: container storage usage in exegol info

[skyf0l]

Add container storage size display to exegol info

Adds a "Storage" column displaying each container's disk usage, excluding the shared base image layers.

Display Modes

Normal mode: Shows total size (container + workspace)

Verbose mode (-v): Shows breakdown

Implementation

• Uses Docker API containers(size=True) to fetch SizeRw (container writable layer)
• Calculates workspace size via os.walk() with symlink safety (followlinks=False)
• Formats sizes using existing ExegolImage.__processSize() helper
• Base image layers are shared across containers (0 MB duplication per container)

Technical Details

• Container size: Changes made on top of the base image (configs, cache, logs, etc.)
• Workspace size: Files in mounted /workspace directory
• Total displayed: Sum of both in normal mode, breakdown in verbose mode

[Dramelac]

Thanks for this PR, this is a very good idea!
I'll put it on hold for now because there is some change I want to make to access the container size directly from DockerUtils and not from ExegolContainer.
I'll update this PR directly myself later