cli: use "escaped-tokens" style for splitting "vlan.xgress-priority-map" list

There should be little difference here, because the priority list is
(and was) never serialized with special characters like backslashes or
delimiters that require escaping.

Likewise, no working code actually tried to set such characters.

Still, drop the plain VALUE_STRSPLIT_MODE_STRIPPED and use
VALUE_STRSPLIT_MODE_ESCAPED_TOKENS_WITH_SPACES instead. We should have
a small set of modes that we use for splitting strings.
7 jobs for <span class="ref-name">th/strsplit-pt4</span> in 51 minutes and 17 seconds (queued for 9 seconds)
Status Job ID Name Coverage
  Test
passed #245954
build_f28

00:32:52

passed #245955
build_f29

00:51:05

failed #245956
build_f30

00:00:24

failed #245957
allowed to fail
build_frawhide

00:18:51

passed #245953
allowed to fail
checkpatch

00:01:01

 
  External
failed NetworkManager test verification

failed NetworkManager test verification

05:55:51

 
Name Stage Failure
failed
build_frawhide Test
UUID=43c9df84-b4e6-4358-ab28-d59424b4e5f0
BASEDIR=/builds/NetworkManager/NetworkManager/contrib/fedora/rpm/NetworkManager.20190418-081234.YHGvm5
warning: Macro expanded in comment on line 137: %{real_version_major}/%{name}-%{real_version}.tar.xz

error: This macro requires some arguments
error: line 809: %systemd_postun

ERROR: rpmbuild FAILED
ERROR: Job failed: exit code 1
failed
build_f30 Test
$ date '+%Y%m%d-%H%M%S'; NM_INSTALL="dnf install -y" ./contrib/fedora/REQUIRED_PACKAGES
20190418-075357
Fedora Modular 30 - x86_64 2.5 MB/s | 2.1 MB 00:00
Fedora Modular 30 - x86_64 - Updates 392 B/s | 257 B 00:00
Fedora Modular 30 - x86_64 - Test Updates 3.6 MB/s | 2.9 MB 00:00
Fedora 30 - x86_64 - Test Updates 16 MB/s | 15 MB 00:00
Fedora 30 - x86_64 - Updates 510 B/s | 257 B 00:00
./contrib/fedora/REQUIRED_PACKAGES: line 13: 11 Segmentation fault (core dumped) $NM_INSTALL "$@"
ERROR: Job failed: exit code 1