Automatic merge from submit-queue (batch tested with PRs 48196, 42783, 48507, 47719, 46138)

IPv6 support for getting IP from default route

This is another part of the effort to update ChoseHostInterface() to support
IPv6. In particular, this focuses on the call path, starting from
chooseHostInterfaceFromRoute(), which attempts to find the node IP by
using default route information.

In the original code, routes are collected, and examined to find default
routes. For a default route, the IPs for the associated interface are
checked to see if there is one that is a V4 address, and is not a
loopback, link local, or multicast address. If found, that IP will be
used for the node IP.

With this PR, there are some slight changes to prepare for allowing IPs
from IPv6 default routes. The routes (IPv4 at this time - a subsequent
PR will handle IPv6) are collected as before. If the route is a default
route AND it's GW address is a global unicast address, then the IPs
for the associated interface are checked. This time though, we just pick
the IP that is on the same subnet as the gateway IP.

This ensures it is not a link local, loopback, or multicast address. It
saves time, by nt checking IPs for interfaces that don't have a "global"
default route. It also will ensure the right IP is used, when using both
IPv4 and IPv6 addresses.

For example, if we have eth0 with global IPv4 and IPv6 addresses, and
an IPv6 default route, we want to select the IPv6 address, as it is
associated with the default route.

Another case is that same interface, along with eth1 containing an IPv4
address with a default route. We want to select eth1's IPv4 address,
and not the IPv4 on eth0.

This change adds more UT coverage to several methods, and removes UTs
that are redundantly testing at a higher level. Coverage is slightly
improved.



**What this PR does / why we need it**:

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: xref #44848

**Special notes for your reviewer**:
This goes along with PR 46044, and will have another PR to the next part.

**Release note**:

```release-noteNONE
```