Imported commands cannot be used in extern/command definition completions

Describe the bug

If you are importing a command (use <module> <command> or using the [<command>] notation), Nushell v0.79.0 will throw an error if you try to use it in an extern or command definition's parameter/flag autocompletion (string@<command>).

How to reproduce

1. Create a module that exports a completion command
2. Create a module that imports the completion command and exports an extern
3. In the extern, write its first parameter like foo: string@<completion command>

Expected behavior

Nushell should not throw an error if an imported command is used in a parameter/flag autocompletion.

Screenshots

Configuration

Additional context

Below are the contents of the files surrounding this error:

ssh.completions.nu

export def "nu-complete ssh destination" [] {
  open `~/.ssh/config`
    | lines
    | where $it starts-with `Host `
    | each { parse `Host {destination}` }
    | flatten
    | $in.destination?
    | where not ($it | is-empty)
    | default []
}

ssh.externs.nu

use ssh.completions.nu `nu-complete ssh destination`

extern ssh [
  destination: string@'nu-complete ssh destination'
]

Reproduce the error using the provided ssh.completions.nu and ssh.externs.nu examples, focusing on the imported nu-complete ssh destination command used in the extern parameter. Trace the command-resolution path for imported completion commands; done means the extern loads and completion works without an error.