filter-repo: send blobs through RepoFilter._insert_into_stream()

We send commits through RepoFilter._insert_into_stream(), and objects
added by the user will go through this function as well.  If we want
to be able to intercept all objects in one place (e.g. to see what LFS
objects are still referenced by the new history), it will be easier if
we ensure blobs also go through this function.

Signed-off-by: Elijah Newren <newren@gmail.com>

Author: newren

git-filter-repo

@@ -3657,6 +3657,8 @@ class RepoFilter(object):
     if self._blob_callback:
       self._blob_callback(blob, self.callback_metadata())
 
+    self._insert_into_stream(blob)
+
   def _filter_files(self, commit):
     def filename_matches(path_expression, pathname):
       ''' Returns whether path_expression matches pathname or a leading