[networking] List contents of netplan configuration dirs

If a user uses `.yml` for a netplan configuration file, netplan
silently ignores it. This at least gives us better visibility without
needing to worry about obfuscating the contents of other (possibly
malformatted) files.

Signed-off-by: Wesley Hershberger <wesley.hershberger@canonical.com>

sos/report/plugins/networking.py

@@ -349,6 +349,14 @@ def setup(self):
             "/run/systemd/network"
         ])
 
+        # Netplan only consumes files with the `.yaml` extension (LP#1815734),
+        # so give visibility on other files that might be present.
+        self.add_dir_listing([
+            "/etc/netplan",
+            "/lib/netplan",
+            "/run/netplan",
+        ])
+
     def postproc(self):
 
         self.do_path_regex_sub(