Use tasks to perform heavy computations in the background

[ghislainv]

This will avoid QGIS to freeze.

See tutorial here: https://docs.qgis.org/3.28/en/docs/pyqgis_developer_cookbook/tasks.html

[ghislainv]

Done. QgsTaskManager has also been used to parallelize long running background tasks. For example, prediction tasks using three statistical models at two dates (6 tasks) are run in parallel.