guidance-ui: display progress info

Just send a simple notification so progress info updates can be tested
as well.

Apertis: https://phabricator.apertis.org/T2814



Signed-off-by: Guillaume Desmottes <guillaume.desmottes@collabora.co.uk>
Reviewed-by: Justin Kim <justin.kim@collabora.com>
Differential Revision: https://phabricator.apertis.org/D5376