FIR Java: support Kotlin extension overriding: at last, #KT-29937 Fixed

idea/testData/fir/multiModule/javaInheritsKotlinExtension/jvm/Base.txt

@@ -0,0 +1,10 @@
+FILE: Base.kt
+    public abstract interface First {
+    }
+    public open class Second {
+        public constructor(): super<R|kotlin/Any|>()
+
+        public open function foo R|First|.(s: R|kotlin/String|, i: R|kotlin/Int|): R|kotlin/Unit| {
+        }
+
+    }