Intentions: Implement "Convert sealed class to enum" intention

#KT-14245 Fixed

idea/resources/intentionDescriptions/ConvertSealedClassToEnumIntention/before.kt.template

@@ -0,0 +1,9 @@
+sealed class MyClass(val s: String = "") {
+    fun foo() {
+
+    }
+
+    object FOO : MyEnum("FOO")
+    object BAR : MyEnum("BAR")
+    object DEFAULT : MyEnum()
+}