dedicated inference CLI improvements

[habfast]

Description

As in the ticket: sc-165040

• exo ai model list and exo ai deployment list don't list in all zones like other commands do
• exo ai model download should be an alias for exo ai model create
• exo ai model show and exo ai model delete should behave like deployments, and be able to search models by name
• exo ai model show and exo ai model list should show model size in GiB

Checklist

(For exoscale contributors)

• Changelog updated (under Unreleased block)
• Testing

Testing

• Unit tests
• Works on my machine...