[Bug] Graphical Modeler: reading coordinates from map window does not work

[landam]

Describe the bug
Reading coordinates from map window fails for tools like r.what called from Graphical Modeler.

To Reproduce
Steps to reproduce the behavior:

1. Open Graphical Modeler from GUI
2. Add r.what to the model
3. Go to Query tab
4. By 'arrow' icon try to read coordinates from map window

Fails with

Traceback (most recent call last):
  File "/home/martin/src/grass/dist.x86_64-pc-linux-
gnu/gui/wxpython/gui_core/gselect.py", line 2847, in
_onClick

self.mapWin = self._giface.GetMapWindow()
AttributeError: 'GraphicalModelerGrassInterface' object has no attribute
'GetMapWindow'

Expected behavior
Coordinates should be read from map window and stored to coordinates option.

Screenshot

System description (please complete the following information):

• Operating System: Linux
• GRASS GIS version: 8.4.0dev

[landam]

Originally reported in #3003 (review)