Refactors font size handling using RimFontSizeField

Replaces direct PdmField usage for font sizes with the new
RimFontSizeField. This provides a consistent way to manage font
size options across different plot types.

The RimFontSizeField encapsulates the logic for generating font size
options based on the default plot font size from preferences. This
removes redundant code in various plot classes and ensures that font
size settings are synchronized with user preferences.

ApplicationLibCode/ProjectDataModel/Rim3dView.cpp

@@ -1517,6 +1517,7 @@ QList<caf::PdmOptionItemInfo> Rim3dView::calculateValueOptions( const caf::PdmFi
     }
     else if ( fieldNeedingOptions == &m_fontSize )
     {
+        // Not possible to use RimFontSizeField, as the values are computed based on defaultSceneFontSize()
         options = caf::FontTools::relativeSizeValueOptions( RiaPreferences::current()->defaultSceneFontSize() );
     }
     else if ( fieldNeedingOptions == &m_scaleZ )