Gui: Use getObject<T>() helpers in classes

This commit is generated using regex based find and replace:

```
s/[\w:]+_cast\s*<([^>]+)\*>\s*\(\s*getObject\(\s*\)\)/getObject<$1>/
s/[\w:]+_cast\s*<([^>]+)\*>\s*\(\s*([^)]*)\s*->\s*getObject\(\s*\)\)/$2->getObject<$1>()/
```

To regenerate if needed.

src/Mod/PartDesign/Gui/TaskDatumParameters.cpp

@@ -90,7 +90,7 @@ bool TaskDlgDatumParameters::reject() {
 
 bool TaskDlgDatumParameters::accept() {
 
-    Part::Datum* pcDatum = static_cast<Part::Datum*>(ViewProvider->getObject());
+    Part::Datum* pcDatum = ViewProvider->getObject<Part::Datum>();
     auto pcActiveBody = PartDesignGui::getBodyFor(pcDatum, false);
     auto pcActivePart = PartDesignGui::getPartFor(pcActiveBody, false);
     std::vector<App::DocumentObject*> copies;