KT-11295 AssertionError in ConvertToStringTemplateIntention.fold

#KT-11295 Fixed

idea/src/org/jetbrains/kotlin/idea/intentions/ConvertToStringTemplateIntention.kt

@@ -99,7 +99,8 @@ class ConvertToStringTemplateIntention : SelfTargetingOffsetIndependentIntention
                 val type = bindingContext.getType(expression)!!
 
                 if (KotlinBuiltIns.isChar(type)) {
-                    return expressionText.removePrefix("'").removeSuffix("'")
+                    val value = expressionText.removePrefix("'").removeSuffix("'")
+                    return if (value == "\"") "\\\"" else value
                 }
 
                 val constant = ConstantExpressionEvaluator.getConstant(expression, bindingContext)

idea/testData/intentions/convertToStringTemplate/kt11295.kt

@@ -0,0 +1,5 @@
+val TABLE_PREFIX = ""
+
+fun test(): String {
+    return <caret>TABLE_PREFIX + '"'
+}

idea/testData/intentions/convertToStringTemplate/kt11295.kt.after

@@ -0,0 +1,5 @@
+val TABLE_PREFIX = ""
+
+fun test(): String {
+    return <caret>"$TABLE_PREFIX\""
+}

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

@@ -4735,6 +4735,12 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
             doTest(fileName);
         }
 
+        @TestMetadata("kt11295.kt")
+        public void testKt11295() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/convertToStringTemplate/kt11295.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("multilineString.kt")
         public void testMultilineString() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/convertToStringTemplate/multilineString.kt");