This completes the refactor of the nxos modules to use the persistent
connection. It also updates all of the nxos modules to use the
new connection module and preserves use of nxapi as well.
When setting state=absent the nxos_nxapi module would always try to remove
the configuration regardless of the current state of the device. This will
fix that problem.
This also updates the docstring to correctly reflect https as default=no
fixes#4955
depends on ansible/ansible#17728