When we use the option archive it could be nice to de-archive just one database inside another database which have a different name.

The actual use case is this one:
1. I have a mongo database created by a SaaS, this service give one database
2. I dump this database as an archive (Archive is used because of the necessity to dump it as a stream using stdout)
3. I want to restore my database to a new created database created from SaaS wich have a different database name than the original one
4. I'm blocked cause it's not possible with --archive option when restoring, it wants to create a database with the name from the original database which is not possible to use

Behavior of the option --targetDb in mongorestore:

• this can only be used when using --archive option
• This option make mongorestore to restore just one database at once
• If you have more than one database in archive and user use --targetDb it will fail, in this case it will ask to set also the option --db
• else mongorestore will take the only database set in archive and restore it in the database set in --targetDb