[FIR] Introduce extension unwrapFakeOverridesOrDelegated()

compiler/fir/tree/src/org/jetbrains/kotlin/fir/ClassMembers.kt

@@ -78,6 +78,9 @@ inline val <reified S : FirCallableSymbol<*>> S.baseForIntersectionOverride: S?
 inline fun <reified D : FirCallableDeclaration> D.originalIfFakeOverride(): D? =
     originalForSubstitutionOverride ?: baseForIntersectionOverride
 
+inline fun <reified D : FirCallableDeclaration> D.originalIfFakeOverrideOrDelegated(): D? =
+    originalForSubstitutionOverride ?: baseForIntersectionOverride ?: delegatedWrapperData?.wrapped
+
 inline fun <reified S : FirCallableSymbol<*>> S.originalIfFakeOverride(): S? =
     fir.originalIfFakeOverride()?.symbol as S?
 
@@ -100,6 +103,15 @@ inline fun <reified D : FirCallableDeclaration> D.unwrapFakeOverrides(): D {
     } while (true)
 }
 
+inline fun <reified D : FirCallableDeclaration> D.unwrapFakeOverridesOrDelegated(): D {
+    var current = this
+
+    do {
+        val next = current.originalIfFakeOverrideOrDelegated() ?: return current
+        current = next
+    } while (true)
+}
+
 inline fun <reified D : FirCallableDeclaration> D.unwrapSubstitutionOverrides(): D {
     var current = this
 
@@ -168,3 +180,16 @@ private object IsCatchParameterProperty : FirDeclarationDataKey()
 
 var FirProperty.isCatchParameter: Boolean? by FirDeclarationDataRegistry.data(IsCatchParameterProperty)
 
+private object DelegatedWrapperDataKey : FirDeclarationDataKey()
+
+class DelegatedWrapperData<D : FirCallableDeclaration>(
+    val wrapped: D,
+    val containingClass: ConeClassLikeLookupTag,
+    val delegateField: FirField,
+)
+
+var <D : FirCallableDeclaration>
+        D.delegatedWrapperData: DelegatedWrapperData<D>? by FirDeclarationDataRegistry.data(DelegatedWrapperDataKey)
+
+val <D : FirCallableDeclaration> FirCallableSymbol<out D>.delegatedWrapperData: DelegatedWrapperData<D>?
+    get() = fir.delegatedWrapperData