Kapt: add some JeElement tests

(cherry picked from commit 948a4b6)

plugins/annotation-processing/testData/elements/IsFunctionalInterface.kt

@@ -0,0 +1,22 @@
+class A {
+    interface AA {
+        fun onClick(o: Any)
+    }
+}
+
+enum class B { RED }
+
+interface C {
+    fun onClick()
+}
+
+interface D {
+    fun onClick()
+    fun onDoubleClick()
+}
+
+interface E : C
+
+interface F : C {
+    fun onDoubleClick()
+}