Fixed AttributeError in ProgressBar in case sys.stderr is None. Added tests for processing module.

This fixes the following AttributeError in case sys.stderr is None which is ...

usually the case for Windows GUI apps that aren’t connected to a console and Python apps started with pythonw.

Traceback (most recent call last):
File "C:\Users/PedroVenancio/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\Coregistration\automated_local_coregistration_algorithm.py", line 278, in processAlgorithm
CRL.correct_shifts()
File "C:\Users\PedroVenancio\AppData\Roaming\QGIS\QGIS3\profiles\default\python\plugins\Coregistration\extlibs_windows\arosics\CoReg_local.py", line 810, in correct_shifts
self.calculate_spatial_shifts()
File "C:\Users\PedroVenancio\AppData\Roaming\QGIS\QGIS3\profiles\default\python\plugins\Coregistration\extlibs_windows\arosics\CoReg_local.py", line 480, in calculate_spatial_shifts
self._tiepoint_grid.get_CoRegPoints_table()
File "C:\Users\PedroVenancio\AppData\Roaming\QGIS\QGIS3\profiles\default\python\plugins\Coregistration\extlibs_windows\arosics\Tie_Point_Grid.py", line 419, in get_CoRegPoints_table
bar.print_progress((i + 1) / len(GDF) * 100)
File "C:\Users\PedroVenancio\AppData\Roaming\QGIS\QGIS3\profiles\default\python\plugins\Coregistration\extlibs_windows\py_tools_ds\processing\progress_mon.py", line 124, in print_progress
self.out.write('\r')
AttributeError: 'NoneType' object has no attribute 'write'

See here.