network: ResolveOrDropHostnames doesn't preserve address meta-information

[Roger Peppe]

ResolveOrDropHostnames resolves a set of hostnames to their IP addresses.
The input hostnames contain network scope information (and SpaceName
and SpaceProviderId), which is not preserved in the resolved
IP addresses.

This metadata should probably should be preserved rather than guessing
from the form of the addresses as it does now.

[Roger Peppe (rogpeppe)]

This seems to be working as intended. The IP addresses after resolving
may well have a different scope to the host name they're derived from,
so scope inference is the only way to find that out, and scope information
is actually preserved when the address already numeric.