K2: support DELEGATION member kind for properties #KT-62581 Fixed

compiler/fir/fir-serialization/src/org/jetbrains/kotlin/fir/serialization/FirElementSerializer.kt

@@ -440,7 +440,7 @@ class FirElementSerializer private constructor(
             hasAnnotations,
             ProtoEnumFlags.visibility(normalizeVisibility(property)),
             ProtoEnumFlags.modality(modality),
-            ProtoBuf.MemberKind.DECLARATION,
+            property.memberKind(),
             property.isVar, hasGetter, hasSetter, hasConstant, property.isConst, property.isLateInit,
             property.isExternal, property.delegateFieldSymbol != null, property.isExpect
         )
@@ -492,6 +492,13 @@ class FirElementSerializer private constructor(
         return builder
     }
 
+    private fun FirProperty.memberKind(): MemberKind {
+        return when (origin) {
+            FirDeclarationOrigin.Delegated -> MemberKind.DELEGATION
+            else -> MemberKind.DECLARATION
+        }
+    }
+
     fun functionProto(function: FirFunction): ProtoBuf.Function.Builder? = whileAnalysing(session, function) {
         val builder = ProtoBuf.Function.newBuilder()
         val simpleFunction = function as? FirSimpleFunction