FirProperty: return back 'isReferredViaField' attribute

compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/FirDeclarationUtil.kt

@@ -116,6 +116,8 @@ fun FirRegularClass.addDeclaration(declaration: FirDeclaration) {
 
 private object IsFromVarargKey : FirDeclarationDataKey()
 var FirProperty.isFromVararg: Boolean? by FirDeclarationDataRegistry.data(IsFromVarargKey)
+private object IsReferredViaField : FirDeclarationDataKey()
+var FirProperty.isReferredViaField: Boolean? by FirDeclarationDataRegistry.data(IsReferredViaField)
 
 inline val FirProperty.hasJvmFieldAnnotation: Boolean
     get() = annotations.any {

compiler/fir/tree/src/org/jetbrains/kotlin/fir/symbols/impl/FirVariableSymbol.kt

@@ -32,10 +32,7 @@ open class FirPropertySymbol(
     constructor(name: Name) : this(CallableId(name))
 }
 
-class FirBackingFieldSymbol(
-    callableId: CallableId,
-    var isReferenced: Boolean = false
-) : FirVariableSymbol<FirProperty>(callableId)
+class FirBackingFieldSymbol(callableId: CallableId) : FirVariableSymbol<FirProperty>(callableId)
 
 class FirDelegateFieldSymbol<D : FirVariable<D>>(callableId: CallableId) : FirVariableSymbol<D>(callableId) {
     val delegate: FirExpression