Fixed KT-5985 Smart completion does not insert comma for constructor of nested data class

#KT-5985 Fixed

idea/testData/completion/handlers/smart/NestedDataClassComma.kt

@@ -0,0 +1,9 @@
+class Outer {
+    private data class Nested(val v: Int, val v2: Int)
+
+    fun foo(p: Int): Inner {
+        return Outer.Nested(<caret>)
+    }
+}
+
+// ELEMENT: p

idea/testData/completion/handlers/smart/NestedDataClassComma.kt.after

@@ -0,0 +1,9 @@
+class Outer {
+    private data class Nested(val v: Int, val v2: Int)
+
+    fun foo(p: Int): Inner {
+        return Outer.Nested(p, <caret>)
+    }
+}
+
+// ELEMENT: p