Consolidate CLI formatting infrastructure

[realrajaryan]

Motivation and Context

This PR consolidates duplicated list-output formatting across the CLI into shared rendering infrastructure.

Currently, each list command has its own copy of the same json/quiet/table branching. This PR pulls that into shared rendering infrastructure in ContainerCommands:

• ListDisplayable protocol for table + quiet output
• renderJSON, renderTable, renderList as pure functions that return strings
• emit() as the single stdout boundary (no-ops on empty strings to avoid blank-line regressions)
• JSONOptions so all JSON encoding goes through one path, including volume inspect's pretty + ISO 8601 case

JSON encoding remains separate from display formatting: each command still chooses its own JSON model, while ListDisplayable is used only for table and quiet output. ImageList remains the intentional exception for quiet mode so it can avoid unnecessary async work.

This change also replaces inline JSONEncoder usage with renderJSON, removes the old Codable+JSON.swift helper, and moves TableOutput and ListFormat into ContainerCommands. It also adds unit tests for the shared rendering helpers and expands integration coverage for image, network, and registry list formatting.

Testing

• Tested locally
• Added/updated tests
• Added/updated docs

[jglogan]

Prefer methods and properties to free functions (avoids cluttering the global namespace):

https://www.swift.org/documentation/api-design-guidelines/

Also: a helper function could reduce a little bit of boilerplate everywhere:

    public func renderOutput<T: ListDisplayable & Encodable>(                                                                                                                                                                                                   
        _ items: [T], format: ListFormat, quiet: Bool                                                                                                                                                                                                           
    ) throws -> String {                                                                                                                                                                                                                                        
        format == .json ? try renderJSON(items) : renderList(items, quiet: quiet)                                                                                                                                                                               
    }