core (memory): files are now public by default except for those in root directory:

using public permissions by default makes permissions change more easy as we don't have to
recursively change all permissions of sub files when changing directory. Root directories
are private by default.

sat/memory/sqlite.py

@@ -1426,7 +1426,7 @@ class Updater(object):
         )
         statements.extend([
             f"INSERT INTO files({cols}) SELECT {old_cols} FROM files_old",
-            f"DROP TABLE files_old",
+            "DROP TABLE files_old",
         ])
         statements.extend(Updater.indexData2Raw(index))
         return statements