Conversion Host Enablement - Configuration Wizard - Submit Conversion Host SSH private key at enable time

[mturley]

Part of the Conversion Hosts UI feature BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1693339

Originally part of #855, I'm disabling this field in the UI until the back end support is ready.

I don't think we can release the Conversion Host settings page without this support.

This issue is for the first of these two SSH keys collected in the Authentication step of the wizard (Conversion Host SSH private key):

The back end support for this key will be ready when ManageIQ/manageiq#18309 is merged. It will need to be passed as the ssh_key field of the POST /api/conversion_hosts request.

The other SSH key is tracked separately in #899.