This allows external service pre-create a neutron port with
'binding:host_id' populated before passing the port to kuryr.
This is important because setting 'binding:host_id' is slow.
This blocks the docker daemon for serving other requests,
which blocks the whole system.
We want to have this field pre-populated so that the docker
daemon won't be blocked by this API call.
This commit also allows the 'device_owner' field to be
customized if users choose to pre-populate the 'binding:host_id'
field. In addition, this commit skips the API call to update the
neutron port if the 'binding:host_id' is pre-populated
and 'admin_state_up' and 'mac_address' fields are unchanged.
Closes-Bug: #1809306
Change-Id: I09c4a51410dffaec21ab0bb3db85df8c776c92e5
5fb8275d12