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/ViewProvider.cpp

@@ -214,7 +214,7 @@ QIcon ViewProvider::mergeColorfulOverlayIcons (const QIcon & orig) const
 
 bool ViewProvider::onDelete(const std::vector<std::string> &)
 {
-    PartDesign::Feature* feature = static_cast<PartDesign::Feature*>(getObject());
+    PartDesign::Feature* feature = getObject<PartDesign::Feature>();
 
     App::DocumentObject* previousfeat = feature->BaseFeature.getValue();