CLI subcommands displayed by error should be sorted

Component

• CLI
• SDK
• Something else
• Not sure

What was the expected behaviour

‣ ./target/debug/oxide system networking bgp
error: 'oxide system networking bgp' requires a subcommand but one was not provided
  [subcommands: announce, announce-set, announcement, auth, config, exported, filter, help, history, imported, peer, pref, show-status, status, withdraw]

What is the current behaviour and what actions did you take to get there

‣ ./target/debug/oxide system networking bgp
error: 'oxide system networking bgp' requires a subcommand but one was not provided
  [subcommands: config, announce-set, announcement, exported, history, imported, status, show-status, peer, announce, withdraw, filter, auth, pref, help]

CLI or SDK version

‣ ./target/debug/oxide version Oxide CLI 0.14.0+20251008.0.0 Built from commit: 916dc54742d119ee043234ce62615e96ce3cbe61 Oxide API: 20251208.0.0

Operating system

MacOS Tahoe 26.1

Anything else you would like to add?

It's a little inconvenient to read the available subcommands returned by an error (e.g. specifying a command without required arguments) when they are not sorted. It would be a better user experience if these were sorted like they are when using --help.

I'm sure this is likely an artifact of clap, but if it's something that we can help then I think it would be nice (albeit low priority) to do so.

Reproduce the missing-subcommand error with oxide system networking bgp, then compare its subcommand order with the output from --help. Inspect the CLI command definitions and the reported clap behavior. Done means the error lists available subcommands in sorted order, matching the help output.