Convert member to extension: Support members of header/impl classes

#KT-18883 Fixed

idea/testData/multiModuleQuickFix/memberFunToExtensionByHeader/header/header.kt

@@ -0,0 +1,5 @@
+// "Convert member to extension" "true"
+
+header class Foo {
+    fun <caret>foo(n: Int)
+}

idea/testData/multiModuleQuickFix/memberFunToExtensionByHeader/header/header.kt.after

@@ -0,0 +1,6 @@
+// "Convert member to extension" "true"
+
+header class Foo {
+}
+
+header fun Foo.foo(n: Int)

idea/testData/multiModuleQuickFix/memberFunToExtensionByHeader/js/js.kt

@@ -0,0 +1,5 @@
+impl class Foo {
+    impl fun foo(n: Int) {
+
+    }
+}

idea/testData/multiModuleQuickFix/memberFunToExtensionByHeader/js/js.kt.after

@@ -0,0 +1,6 @@
+impl class Foo {
+}
+
+impl fun Foo.foo(n: Int) {
+
+}

idea/testData/multiModuleQuickFix/memberFunToExtensionByHeader/jvm/jvm.kt

@@ -0,0 +1,5 @@
+impl class Foo {
+    impl fun foo(n: Int) {
+
+    }
+}

idea/testData/multiModuleQuickFix/memberFunToExtensionByHeader/jvm/jvm.kt.after

@@ -0,0 +1,6 @@
+impl class Foo {
+}
+
+impl fun Foo.foo(n: Int) {
+
+}