Add Zone fill to undo stack

Allows undoing zone filling and reverting to previous fill state.
Fixes https://gitlab.com/kicad/code/kicad/-/issues/7440

pcbnew/tools/zone_filler_tool.cpp

@@ -132,7 +132,7 @@ void ZONE_FILLER_TOOL::FillAllZones( wxWindow* aCaller, PROGRESS_REPORTER* aRepo
 
     if( filler.Fill( toFill ) )
     {
-        commit.Push( _( "Fill Zone(s)" ), false );
+        commit.Push( _( "Fill Zone(s)" ), true ); // Allow undoing zone fill
         getEditFrame<PCB_EDIT_FRAME>()->m_ZoneFillsDirty = false;
     }
     else
@@ -176,7 +176,7 @@ int ZONE_FILLER_TOOL::ZoneFill( const TOOL_EVENT& aEvent )
     std::lock_guard<KISPINLOCK> lock( board()->GetConnectivity()->GetLock() );
 
     if( filler.Fill( toFill ) )
-        commit.Push( _( "Fill Zone(s)" ), false );
+        commit.Push( _( "Fill Zone(s)" ), true );  // Allow undoing zone fill
     else
         commit.Revert();