superproject: print messages if the manifest has superproject tag.

1) If the manifest has superproject tag (git_master, etc), then
   display error/warning messages (as it is doing today)
2) If the manifest doesn't have superproject tag (nest, chromeos
   manifests), then don't display any error/warning messages about
   superrproject (behave as though user has specified
   --no-use-superproject).
3) Print error/warning messages if --use-superproject passed as
   argument to repo sync.
4) No change in behavior for the repo init command.

git_superproject.py:
+ Fixed typo in _WriteManifestFile method name
+ Superproject accepts print_message  as an argument and it defaults
  to True. All messages that are printed to stderr are controlled by
  this flag. If it is True, then messages get printed.
+ Added PrintMessages function which return true if either
  --use-superproject is specified on the command line or if the
  manifest has a superproject tag.

sync.py:
+ Displays the warning message if PrintMessgages are enabled and
  passes that as argument to superproject object.
+ Added 'hassuperprojecttag' trace2 log entry for analysis. We can
  find users/branches that are using superproject, but the manifest is
  missing the superproject tag.

Tested:
$ ./run_tests

+ Verified printing of messages with and without superproject tag, with
  with --use-superproject option.

+ aosp-master
  $ repo_dev init --use-superproject -u https://android.googlesource.com/platform/manifest
  $ repo_dev sync

+ A manifest without superproject tag.
  $ repo_dev init -m $(pwd)/manifest_7482982.xml
  $ repo_dev sync -n -c -j32 -m $(pwd)/manifest_7482982.xml

Bug: [google internal] b/196411099
Change-Id: I92166dcad15a4129fab82edcf869e7c8db3efd4b
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/314982
Reviewed-by: Xin Li <delphij@google.com>
Tested-by: Raman Tenneti <rtenneti@google.com>

subcmds/sync.py

@@ -298,10 +298,12 @@ later is required to fix a server side protocol bug.
     Returns:
       Returns path to the overriding manifest file instead of None.
     """
+    print_messages = git_superproject.PrintMessages(opt, self.manifest)
     superproject = git_superproject.Superproject(self.manifest,
                                                  self.repodir,
                                                  self.git_event_log,
-                                                 quiet=opt.quiet)
+                                                 quiet=opt.quiet,
+                                                 print_messages=print_messages)
     if opt.local_only:
       manifest_path = superproject.manifest_path
       if manifest_path:
@@ -317,10 +319,11 @@ later is required to fix a server side protocol bug.
     if manifest_path:
       self._ReloadManifest(manifest_path, load_local_manifests)
     else:
-      print('warning: Update of revisionId from superproject has failed, '
-            'repo sync will not use superproject to fetch the source. ',
-            'Please resync with the --no-use-superproject option to avoid this repo warning.',
-            file=sys.stderr)
+      if print_messages:
+        print('warning: Update of revisionId from superproject has failed, '
+              'repo sync will not use superproject to fetch the source. ',
+              'Please resync with the --no-use-superproject option to avoid this repo warning.',
+              file=sys.stderr)
       if update_result.fatal and opt.use_superproject is not None:
         sys.exit(1)
     return manifest_path
@@ -970,6 +973,7 @@ later is required to fix a server side protocol bug.
     superproject_logging_data = {
         'superproject': use_superproject,
         'haslocalmanifests': bool(self.manifest.HasLocalManifests),
+        'hassuperprojecttag': bool(self.manifest.superproject),
     }
     if use_superproject:
       manifest_name = self._UpdateProjectsRevisionId(