Auto-update MSW segments on UI changes (opt-in)

Adds an 'Auto Update Segments' toggle (default: on) to the MSW Segment
Visualization group in WellPathCollection. When enabled, MSW segments
are automatically recomputed and redrawn whenever the user modifies:
- Well path geometry or targets
- Perforation intervals
- Fishbone laterals
- Fractures
- Well path fields

The update is triggered via a new updateMswSegmentsForObject()
method, which resolves the top-level well from the changed object, clears
existing segments for all lateral wells in that group, recomputes segments
using updateSegments(), and schedules a full redraw.

When auto-update is disabled, an 'Update Segments' button is shown
instead, allowing manual control.

ApplicationLibCode/ProjectDataModel/RimTools.cpp

@@ -555,13 +555,7 @@ void RimTools::colorLegendOptionItems( QList<caf::PdmOptionItemInfo>* options )
 //--------------------------------------------------------------------------------------------------
 RimWellPathCollection* RimTools::wellPathCollection()
 {
-    RimProject* proj = RimProject::current();
-    if ( proj && proj->activeOilField() )
-    {
-        return proj->activeOilField()->wellPathCollection();
-    }
-
-    return nullptr;
+    return RimWellPathCollection::instance();
 }
 
 //--------------------------------------------------------------------------------------------------