Add command for deleting other resource types

From the API Services Portal, some resource types can be deleted (Product and ProductEnvironments, CredentialIssuers/Authorization Profiles), but not from `gwa`.

Currently it is only possible to create and update non-GatewayService resources from `gwa` - not delete them.

It is not possible to delete DraftDatasets from Portal or `gwa`, only from the Portal API.

## AC
- Add a command which allows deleting other resource types by `name`

## Notes
- use API `DELETE` endpoints
- will there be errors returned when trying to delete items because on their use in other resource types? might need to consider the deletion order / ensure good error messaging