Gui: Improve transform UI responsivness

This introduces much faster CenterOfMassProvider#supports method that
can be used as cheap pre-check to see if the object supplied could have
the center of mass and so delay the domputation to a moment where it is
actually needed.

src/App/Services.cpp

@@ -27,4 +27,9 @@ std::optional<Base::Vector3d>
 App::NullCenterOfMass::ofDocumentObject([[maybe_unused]] DocumentObject* object) const
 {
     return std::nullopt;
+}
+
+bool App::NullCenterOfMass::supports(DocumentObject* object) const
+{
+    return false;
 }

src/App/Services.h

@@ -55,6 +55,7 @@ class CenterOfMassProvider
 public:
     virtual ~CenterOfMassProvider() = default;
 
+    virtual bool supports(DocumentObject* object) const = 0;
     virtual std::optional<Base::Vector3d> ofDocumentObject(DocumentObject* object) const = 0;
 };
 
@@ -66,6 +67,7 @@ class NullCenterOfMass final : public CenterOfMassProvider
 {
 public:
     std::optional<Base::Vector3d> ofDocumentObject(DocumentObject* object) const override;
+    bool supports(DocumentObject* object) const override;
 };
 
 }