Make TaurusWidgetFactory aware of taurus.qt.qtgui entry point
TaurusWidgetFactory
does not explore modules registered with
the "taurus.qt.qtgui"
entry-point (e.g. taurus_pyqtgraph).
Make it aware of such modules.
Also, add the deprecated plot
and styles
modules to the list
of skipped modules during TaurusWidgetFactory
exploration to
avoid deprecation warnings during initialization.