Add inspection: Refactor sealed sub-class to object #KT-20305 Fixed

idea/testData/multiFileLocalInspections/convertSealedSubClassToObject/convertInOtherFiles/after/JavaSealedTest.java

@@ -0,0 +1,13 @@
+import seal.*
+
+class JavaSealedTest {
+    Sealed sealedInsideClass = SubSealed.INSTANCE;
+
+    public void testSeal() {
+        Sealed sealedInsideMethod = SubSealed.INSTANCE;
+
+        SubSealed.INSTANCE.toString();
+
+        // Will be deleted because Java doesn't allow a expression to be used as a statement
+    }
+}

idea/testData/multiFileLocalInspections/convertSealedSubClassToObject/convertInOtherFiles/after/KotlinSealedTest.kt

@@ -0,0 +1,13 @@
+import seal.*
+
+val sealedOutsideClass = SubSealed
+
+class KotlinSealedTest {
+    val sealedInsideClass = SubSealed
+
+    fun testSeal() {
+        val sealedInsideMethod = SubSealed
+
+        SubSealed
+    }
+}

idea/testData/multiFileLocalInspections/convertSealedSubClassToObject/convertInOtherFiles/after/Seal.kt

@@ -0,0 +1,5 @@
+package seal
+
+sealed class Sealed
+
+object SubSealed : Sealed()