Polygon filter updates (#7216)

* Rename polylinefilter to polygonfilter
* Update icon name, too
* Some GUI adjustments
* Remove obsolete code that came back in a merge somewhere.
Disable auto-enable polygon filter after picking corner points.
* Add option to delete a point in polygon filter point editor by extending generic picker interface
* Rename enum, too.
* Improved filter naming

Co-authored-by: Magne Sjaastad <magne.sjaastad@ceetronsolutions.com>

ApplicationExeCode/Resources/ResInsight.qrc

@@ -223,13 +223,13 @@
         <file>Close.svg</file>
         <file>Refresh.svg</file>
         <file>CellFilter.png</file>
-        <file>CellFilter_Polyline.png</file>
         <file>FilterFunction.svg</file>
         <file>FilterParameter.svg</file>
         <file>ObjectiveFunction.svg</file>
         <file>ObjectiveFunctionCollection.svg</file>
         <file>ObjectiveFunctionWeight.svg</file>
         <file>CellFilter_UserDefined.png</file>
+        <file>CellFilter_Polygon.png</file>
     </qresource>
     <qresource prefix="/Shader">
         <file>fs_CellFace.glsl</file>