wifi: guess metered flag based on Network Cost information element

Network Cost [1] is a vendor-specific information element defined by
Microsoft and used to advertise the cost of Wi-Fi networks to clients.

We can use it together with the ANDROID_METERED mechanism to
automatically set the metered flag on the device.

[1] https://docs.microsoft.com/en-us/windows-hardware/drivers/mobilebroadband/network-cost-information-element

#200
17 jobs for bg/wifi-network-cost-ie in 70 minutes (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #588691
allowed to fail
checkpatch

00:01:04

manual #588696
allowed to fail manual
t_centos:7.5.1804
passed #588697
t_centos:7.6.1810

00:26:28

passed #588703
t_debian:10

00:21:26

passed #588702
t_debian:9

00:21:27

passed #588705
t_debian:sid

00:21:23

manual #588704
allowed to fail manual
t_debian:testing
passed #588692
t_fedora:28

00:31:49

passed #588693
t_fedora:29

00:41:14

passed #588694
t_fedora:30

00:33:17

manual #588695
allowed to fail manual
t_fedora:rawhide
passed #588698
t_ubuntu:16.04

01:09:57

passed #588699
t_ubuntu:18.04

00:24:38

manual #588701
allowed to fail manual
t_ubuntu:devel
manual #588700
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/689/

failed https://desktopqe-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/job/beaker-NetworkManager-gitlab-trigger-code-upstream/689/

07:29:12