fixed #6544. Add Folder issue for adding a sub-folder inside a folder.

Issue root cause is "/" omitted while `file_path` is making from `path` and `name`.
Fixed the issue of sub-folder adding issue by adding a process to check "/" is end of the `path` or start of the `name`.

web/pgadmin/misc/file_manager/__init__.py

@@ -947,6 +947,8 @@ def get_new_name(in_dir, path, name):
         new_name = name
         count = 0
         while True:
+            if not (path.endswith("/") or name.startswith("/")):
+                path = path + "/"
             file_path = "{}{}/".format(path, new_name)
             create_path = file_path
             if in_dir != "":