Do not show "Convert to extension" intention for secondary constructors

#KT-6969 Fixed

idea/src/org/jetbrains/kotlin/idea/intentions/declarations/ConvertMemberToExtension.java

@@ -71,6 +71,7 @@ public class ConvertMemberToExtension extends BaseIntentionAction {
             if (((JetProperty) declaration).hasInitializer()) return false;
         }
         return declaration != null
+               && !(declaration instanceof JetSecondaryConstructor)
                && declaration.getParent() instanceof JetClassBody
                && declaration.getParent().getParent() instanceof JetClass
                && declaration.getReceiverTypeReference() == null;

idea/testData/intentions/declarations/convertMemberToExtension/secondaryConstructor.kt

@@ -0,0 +1,4 @@
+// IS_APPLICABLE: false
+class A {
+    <caret>constructor() {}
+}

idea/tests/org/jetbrains/kotlin/idea/intentions/IntentionTestGenerated.java

@@ -4014,6 +4014,12 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("secondaryConstructor.kt")
+            public void testSecondaryConstructor() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("idea/testData/intentions/declarations/convertMemberToExtension/secondaryConstructor.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("simple.kt")
             public void testSimple() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("idea/testData/intentions/declarations/convertMemberToExtension/simple.kt");