Support right_format in nushell

[zbraniecki]

Nushell supports dual input (left and right side), but when switching to starship I can't use it.

For example, this cannot be recreated in starship because the date/time cannot be displayed on the right in Nushell:

[davidkna]

See also nushell/nushell#4909 on why starship does not enable right prompt with nushell by default.

In your specific case, because your prompt is single-line, this might work for you:

let-env PROMPT_COMMAND_RIGHT = {
    let width = (term size -c | get columns | into string)
    starship prompt --right $"--cmd-duration=($env.CMD_DURATION_MS)" $"--status=($env.LAST_EXIT_CODE)" $"--terminal-width=($width)"
}

Warning: This snippet may need to be updated as nushell and starship evolve.

#3177 may also solve this.