Fix ADL lookup for cvf pdmToVariant/pdmFromVariant overloads

Move pdmToVariant/pdmFromVariant overloads for cvf::Color3f, Vec3d, Mat4d, and
Mat3d from namespace caf to namespace cvf. Templates in
cafInternalPdmFieldTypeSpecializations.h use "using caf::pdmToVariant" followed
by an unqualified call, so ADL searches the argument's namespace (cvf). With the
overloads only in caf, the default template was selected, causing cvf::Color3f to
be stored raw in a QVariant instead of as QColor — breaking color field editing
and producing QVariant::save warnings.

All call sites now use the unqualified "using caf::pdmXxx; pdmXxx(value)" pattern
so ADL finds the correct overload without depending on cvf:: as a visible prefix.
Add AdlVariantTest to cafPdmCoreColor3fTest.cpp that exercises this exact pattern.

Adds caf::toVariant<T> and caf::fromVariant<T> to cafPdmFieldTraits.h as
thin wrappers that encapsulate the ADL two-step internally. Client code can
now call caf::toVariant(x) directly instead of requiring a using-declaration
at every call site.

Fwk/AppFwk/cafProjectDataModel/cafPdmCore/cafPdmFieldTraits.h

@@ -120,6 +120,29 @@ void pdmFromVariant( const QVariant& v, std::optional<T>& out )
     out = underlying;
 }
 
+//==================================================================================================
+/// toVariant / fromVariant — public API wrappers
+///
+/// Simple qualified-call entry points that encapsulate the ADL two-step internally.
+/// Prefer these over calling pdmToVariant/pdmFromVariant with a using-declaration at the call site.
+/// Custom types are still extended by adding pdmToVariant/pdmFromVariant overloads in the type's
+/// own namespace; these wrappers just hide that detail from callers.
+//==================================================================================================
+
+template <typename T>
+QVariant toVariant( const T& value )
+{
+    using caf::pdmToVariant;
+    return pdmToVariant( value );
+}
+
+template <typename T>
+void fromVariant( const QVariant& v, T& out )
+{
+    using caf::pdmFromVariant;
+    pdmFromVariant( v, out );
+}
+
 //==================================================================================================
 /// PdmVariantEqualImpl<T>
 ///