KT-20880: Fix AddDocumentationFix to add multiline comment

#KT-20880 fixed

idea/testData/quickfix/kdocMissingDocumentation/simple.kt.after

@@ -1,5 +1,7 @@
 // "Add documentation" "true"
 
-/** <caret> */
+/**
+ * <caret>
+ */
 class C {
 }

idea/testData/quickfix/kdocMissingDocumentation/withIndentation.kt

@@ -0,0 +1,9 @@
+// "Add documentation" "true"
+
+
+class C {
+
+    fun <caret>foo() {
+
+    }
+}

idea/testData/quickfix/kdocMissingDocumentation/withIndentation.kt.after

@@ -0,0 +1,12 @@
+// "Add documentation" "true"
+
+
+class C {
+
+    /**
+     * <caret>
+     */
+    fun foo() {
+
+    }
+}