Generate copy() in data class even if constructor is empty or not present

compiler/testData/diagnostics/tests/dataClasses/noConstructor.kt

@@ -0,0 +1,6 @@
+data class A
+
+fun foo(a: A) {
+    a.<!UNRESOLVED_REFERENCE!>component1<!>()
+    a.<!UNRESOLVED_REFERENCE!>component2<!>()
+}

compiler/testData/loadJava/compiledKotlin/dataClass/NoComponents.kt

@@ -1,3 +1,4 @@
 package test
 
 data class DataClass
+data class OtherDataClass()

compiler/testData/loadJava/compiledKotlin/dataClass/NoComponents.txt

@@ -2,4 +2,10 @@ package test
 
 kotlin.data() internal final class DataClass {
     /*primary*/ public constructor DataClass()
+    internal final /*synthesized*/ fun copy(): test.DataClass
+}
+
+kotlin.data() internal final class OtherDataClass {
+    /*primary*/ public constructor OtherDataClass()
+    internal final /*synthesized*/ fun copy(): test.OtherDataClass
 }