[#46754661]  Fix problem getting Subscriptions to listen to selected folders (instead of all) -- in this case Inbox.

The cause was a namespace problem with FolderIds tag in the request XML.
If the default namespace is used, Exchange rejects the request because it sees the FolderIds tag in the Messages namespace, even though MS docs seem to say that it can exist in either the Messages or Types namespace.
Sending the [] argument namespaces it in Types, the same as the EventTypes tag.
It's possible this could conflict with another usage of FolderIds that need to exist in the Messages namespace.