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

#KT-18883 Fixed

idea/testData/multiModuleQuickFix/memberValToExtensionByHeader/header/header.kt

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

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

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

idea/testData/multiModuleQuickFix/memberValToExtensionByHeader/js/js.kt

@@ -0,0 +1,3 @@
+impl class Foo {
+    impl val foo get() = 1
+}

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

@@ -0,0 +1,4 @@
+impl class Foo {
+}
+
+impl val Foo.foo get() = 1

idea/testData/multiModuleQuickFix/memberValToExtensionByHeader/jvm/jvm.kt

@@ -0,0 +1,3 @@
+impl class Foo {
+    impl val foo get() = 2
+}

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

@@ -0,0 +1,4 @@
+impl class Foo {
+}
+
+impl val Foo.foo get() = 2