Prevent text attachment view from proxying interactions to content view

STTextView would incorrectly handle interactions with text attachment
views, proxying them to the content view instead. This change fixes that by
detecting when the view is a descendant of a text layout fragment view and
avoiding the proxy in that case.

Author: krzyzanowskim

Sources/STTextViewAppKit/STTextView.swift

@@ -756,6 +756,10 @@ import AVFoundation
         if let view = result, view != self,
            (view.isDescendant(of: contentView) || view.isDescendant(of: selectionView))
         {
+            // FIXME: NSTextAttachment view
+            // attachment view is a child of STTextLayoutFragmentView
+            // that itself is child of contentView.
+            // The text attachment view should not proxy interaction to the contentView
             return self
         }
         return result