Adds a Python unit test that just tries to retrieve all child nodes from
the master script provider in order to check that they are all
accessible from Python.
Change-Id: I97185b7f21f38a79fdda4078a69d8e88b10cbaed
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/207349
Tested-by: Jenkins
Reviewed-by: Neil Roberts <nroberts@libreoffice.org>
