fix: inability to add ssh-key to new lagoon

[jackwrfuller]

General Checklist

• Affected Issues have been mentioned in the Closing issues section
• Documentation has been written/updated
• PR title is ready for inclusion in changelog

Description

Currently, it is not possible to add to add an ssh-key to a new Lagoon instance using the following command:

lagoon config add \
        --force \
        --graphql URL \
        --ui URL \
        --hostname IP \
        --lagoon lagoon \
        --port 2020 \
        --ssh-key "/path/to/key"

This is due to a missing dash in the LagoonConfigFlags, as the command flag expects --ssh-key and will not accept --sshkey