Experimental fixes: introduce "add annotation" (KT-22760)

idea/testData/quickfix/experimental/basicFunctionContainingClass.kt.after

@@ -0,0 +1,16 @@
+// "Add '@MyExperimentalAPI' annotation to containing class 'Bar'" "true"
+// COMPILER_ARGUMENTS: -Xuse-experimental=kotlin.Experimental
+// WITH_RUNTIME
+
+@Experimental
+annotation class MyExperimentalAPI
+
+@MyExperimentalAPI
+fun foo() {}
+
+@MyExperimentalAPI
+class Bar {
+    fun bar() {
+        foo()
+    }
+}