core: allow live change of MTU for devices that support it

Allow a live change of MTU using the reapply API for device types that
support it.
20 jobs for bg/parent-mtu-rh1723690 in 37 minutes and 48 seconds (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Test
passed #718848
checkpatch

00:01:07

manual #718854
allowed to fail manual
t_centos:7.5.1804
passed #718855
t_centos:7.6.1810

00:26:16

passed #718861
t_debian:10

00:13:03

passed #718860
t_debian:9

00:18:16

passed #718863
t_debian:sid

00:17:40

manual #718862
allowed to fail manual
t_debian:testing
manual #718849
allowed to fail manual
t_fedora:28
passed #718850
t_fedora:29

00:37:47

passed #718851
t_fedora:30

00:31:20

passed #718852
t_fedora:31

00:30:18

manual #718853
allowed to fail manual
t_fedora:rawhide
passed #718856
t_ubuntu:16.04

00:22:06

passed #718857
t_ubuntu:18.04

00:19:00

manual #718859
allowed to fail manual
t_ubuntu:devel
manual #718858
allowed to fail manual
t_ubuntu:rolling
 
  External
failed https://desktopqe-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/job/beaker-NetworkManager-gitlab-trigger-code-upstream/1486/

failed https://desktopqe-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/job/beaker-NetworkManager-gitlab-trigger-code-upstream/793/

failed https://desktopqe-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/job/beaker-NetworkManager-gitlab-trigger-code-upstream/1486/

01:21:28

failed https://desktopqe-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/job/beaker-NetworkManager-gitlab-trigger-code-upstream/793/

00:40:00