Merge pull request #18384 from michaelnebel/csharp13/escapechars

C# 13: [TEST ONLY] Add test using the new escape char for ESCAPE.

Author: michaelnebel

csharp/ql/test/library-tests/strings/Strings.cs

@@ -0,0 +1,12 @@
+using System;
+
+public class TestClass
+{
+    public void M()
+    {
+        var x1 = "Hello world";
+        var x2 = "\u001b";
+        var x3 = "\x1b";
+        var x4 = "\e";
+    }
+}

csharp/ql/test/library-tests/strings/stringLiterals.expected

@@ -0,0 +1,4 @@
+| Strings.cs:7:18:7:30 | "Hello world" | Hello world |
+| Strings.cs:8:18:8:25 | "\u001b" | \u001b |
+| Strings.cs:9:18:9:23 | "\u001b" | \u001b |
+| Strings.cs:10:18:10:21 | "\u001b" | \u001b |

csharp/ql/test/library-tests/strings/stringLiterals.ql

@@ -0,0 +1,5 @@
+import csharp
+
+query predicate stringLiterals(StringLiteral lit, string value) {
+  lit.fromSource() and value = lit.getValue()
+}