Routes are complicated.
`ip route add` and `ip route append` behaves differently with respect to
determine whether an existing route is idential or not.
Extend the cmp() and hash() functions to have a compare type, that
covers the different semantics.
NMIP4Config, NMIP6Config, and NMPlatform shall share one
NMDedupMultiIndex instance.
For that, pass an NMDedupMultiIndex instance to NMPlatform and NMNetns.
NMNetns than passes it on to NMDevice, NMDhcpClient, NMIP4Config and NMIP6Config.
So currently NMNetns is the access point to the shared NMDedupMultiIndex
instance, and it gets it from it's NMPlatform instance.
The NMDedupMultiIndex instance is really a singleton, we don't want
multiple instances of it. However, for testing, instead of adding a
singleton instance, pass the instance explicitly around.
The "shared" directory contains files that are possibly used by all components
of NetworkManager repository.
Some of these files are even copied as-is to other projects (VPN plugins, nm-applet)
and used there without modification. Move those files to a separate directory.
By moving them to a common directory, it is clearer that they belong
together. Also, you can easier compare the copied versions to their
original via
$ diff -r ./shared/nm-utils/ /path/to/nm-vpn-plugin/shared/nm-utils/
A large part of "nm-test-utils.h" is only relevant for tests inside "src/"
directory, as they are helpers related to NetworkManager core part.
Split this part out of "nm-test-utils.h" header.
