[FIR] Replace usages of FirExpression.typeRef with coneTypeOrNull

#KT-59855 Fixed

plugins/assign-plugin/assign-plugin.k2/src/org/jetbrains/kotlin/assignment/plugin/k2/FirAssignmentPluginAssignAltererExtension.kt

@@ -54,7 +54,7 @@ class FirAssignmentPluginAssignAltererExtension(
             source = variableAssignment.source?.fakeElement(KtFakeSourceElementKind.DesugaredCompoundAssignment)
             explicitReceiver = buildPropertyAccessExpression {
                 source = leftArgument.source
-                typeRef = leftResolvedType
+                coneTypeOrNull = leftResolvedType.type
                 calleeReference = leftArgument
                 (variableAssignment.lValue as? FirQualifiedAccessExpression)?.typeArguments?.let(typeArguments::addAll)
                 annotations += variableAssignment.annotations
@@ -71,4 +71,4 @@ class FirAssignmentPluginAssignAltererExtension(
             origin = FirFunctionCallOrigin.Regular
         }
     }
-}
+}