It turns out we need a way to ignore transient (agent-owned or unsaved)
secrets during connection comparison.  For example, if the user is
connecting to a network where the password is not saved, other
changes could trigger a writeout of that connection to disk when
connecting, which would the connection back in due to inotify, and the
re-read connection would then no longer be recognized as the same as
the in-memory connection due to the transient secret which obviously
wasn't read in from disk.

Adding these compare flags allows the code to not bother writing the
connection out to disk when the only difference between the on-disk
and in-memory connections are secrets that shouldn't get written to
disk anyway.