Don't offer autocompletions for arguments that have already been used.

If I provide a required argument such as `--image-id`, we shouldn't be offering it anymore as an autocomplete option. This would improve the case where you have multiple required params, you can keep adding params until no more required params were autocompleted.

Locate the AWS CLI autocomplete handling and reproduce the case with multiple required parameters, such as --image-id. Verify which arguments have already been supplied and how required arguments are offered; done means used arguments no longer appear while remaining required arguments continue to be suggested.

Written by the indexing model from the issue text.