Draft: close task panels on doc close

Related: #17952.

This PR introduces a document observer to close task panels on doc close.

For now it is for the Draft Workbench only. The BIM Workbench will be dealt with in a future PR.

The basic code is simple, but to make things works some additional things were addressed:
* gui_base.py: the GuiCommandBase class was enhanced to handle App.activeDraftCommand, self.doc, self.view and self.planetracker. Strictly speaking only the first 2 are required for this PR.
* gui_base.py: self.command_name was changed to self.featureName for compatibility with gui_base_original.py. Not required for this PR.
* gui_arcs.py, gui_circulararray.py, gui_polararray.py and gui_orthoarray.py: updated in relation to the GuiCommandBase class.
* gui_arcs.py Arc_3Points: The command now has a ui property and shows a plane tracker. Only the first is required for this PR.
* gui_shapestrings.py: This command had two ui attributes: self.ui and self.task. This was problematic. To fix this the base class of the command was changed from gui_base_original.Creator to gui_base.GuiCommandBase. As a result the getStrings method is no longer available meaning that the useSupport parameter is ignored when creating a ShapeString. But since that mechanism does not work properly anyway, I feel that this is acceptable. Should many user complain the functionality can of course be reintroduced.

src/Mod/Draft/draftutils/doc_observer.py

@@ -0,0 +1,42 @@
+import FreeCAD as App
+
+if App.GuiUp:
+    import FreeCADGui as Gui
+    from draftutils.todo import ToDo
+
+    class _Draft_DocObserver():
+
+        # See: /src/Gui/DocumentObserverPython.h
+
+        def slotDeletedDocument(self, gui_doc):
+            _finish_command_on_doc_close(gui_doc)
+
+    _doc_observer = None
+
+    def _doc_observer_start():
+        global _doc_observer
+        if _doc_observer is None:
+            _doc_observer = _Draft_DocObserver()
+            Gui.addDocumentObserver(_doc_observer)
+
+    def _doc_observer_stop():
+        global _doc_observer
+        try:
+            if _doc_observer is not None:
+                Gui.removeDocumentObserver(_doc_observer)
+        except:
+            pass
+        _doc_observer = None
+
+    def _finish_command_on_doc_close(gui_doc):
+        """Finish the active Draft or BIM command if the related document has been
+        closed. Only works for commands that have set `App.activeDraftCommand.doc`
+        and use a task panel.
+        """
+        if getattr(App, "activeDraftCommand", None) \
+                and getattr(App.activeDraftCommand, "doc", None) == gui_doc.Document \
+                and getattr(App.activeDraftCommand, "ui", None):
+            if hasattr(App.activeDraftCommand.ui, "reject"):
+                ToDo.delay(App.activeDraftCommand.ui.reject, None)
+            elif hasattr(App.activeDraftCommand.ui, "escape"):
+                ToDo.delay(App.activeDraftCommand.ui.escape, None)