cli: abort on extra arguments

Instead of straight-out rejecting extra parameters for various nmcli
sub-commands (such as "nmcli dev status", "nmcli dev wifi rescan" or
"nmcli dev wifi connect", etc.), we just print a warning and go ahead.

This is unhelpful. In case the user makes a typo, we'll do the wrong
thing and possibly even drown the warning in the output.

While at that, let's make the error message consistent. One less string
to tranalate.
15 jobs for lr/cli-extra-argument in 41 minutes and 3 seconds (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Test
passed #457810
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checkpatch

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manual #457815
allowed to fail manual
t_centos:7.5.1804
passed #457816
t_centos:7.6.1810

00:41:02

passed #457822
t_debian:10

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passed #457821
t_debian:9

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passed #457824
t_debian:sid

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manual #457823
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t_debian:testing
passed #457811
t_fedora:28

00:30:49

passed #457812
t_fedora:29

00:40:31

passed #457813
t_fedora:30

00:30:52

manual #457814
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t_fedora:rawhide
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t_ubuntu:16.04

00:28:50

passed #457818
t_ubuntu:18.04

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manual #457820
allowed to fail manual
t_ubuntu:devel
manual #457819
allowed to fail manual
t_ubuntu:rolling