Implement the OSM down-loader functionality

[mvmaltitz]

Using QgsBlockingNetworkRequest or non blocking request, impleent logic that will perform one or more OSM queries (one per polygon part for the analysis area) of the bounding boxes generated during the project setup phases.

I have provided an initial exemplar implementation here:

https://github.com/kartoza/GEEST2/blob/tim/geest/core/osm_data_downloader.py

This needs to be updated to use QgsLogger (see https://qgis.org/pyqgis/3.34/core/QgsLogger.html#module-QgsLogger) rather than printf for status messages that are not user facing.

User facing messages should be shown to the user https://qgis.org/pyqgis/3.34/gui/QgsMessageBar.html#module-QgsMessageBar

For the initial implementation just focus on having a static example of the downloader perfroming a query and saving it to the working dir, and a unit test to show it works properly.

Some pre-requisites for this ticket:

• Implement properties for project
• [ ]

[timlinux]

@hennie-k @mvmaltitz please see https://github.com/kartoza/GEEST2/blob/tim/geest/core/osm_data_downloader.py