C#: Add some examples lambdas with different kind of attributes and update existing testcases.

Author: michaelnebel

csharp/ql/test/library-tests/csharp10/LambdaAttributes.cs

@@ -0,0 +1,18 @@
+using System;
+
+public class Example : Attribute
+{
+    public Example(int x) { }
+}
+
+public class LambdaAttributes
+{
+
+    public void M1()
+    {
+        // Examples needed for attributes.
+        var f7 = ([Example(1)] int x) => x.ToString(); // Parameter attribute
+        var f8 =[Example(2)] (int x) => x.ToString(); // Lambda attribute
+        var f9 =[return: Example(3)] (int x) => x.ToString(); // Return value attribute
+    }
+}

csharp/ql/test/library-tests/csharp10/lambda.expected

@@ -5,11 +5,17 @@ lambdaDeclaration
 | Func<bool, object> | Lambda.cs:17:13:17:14 | f6 | Lambda.cs:17:18:17:45 | (...) => ... |
 | Func<int, string> | Lambda.cs:8:27:8:28 | f1 | Lambda.cs:8:32:8:54 | (...) => ... |
 | Func<int, string> | Lambda.cs:9:13:9:14 | f2 | Lambda.cs:9:18:9:40 | (...) => ... |
+| Func<int, string> | LambdaAttributes.cs:14:13:14:14 | f7 | LambdaAttributes.cs:14:18:14:53 | (...) => ... |
+| Func<int, string> | LambdaAttributes.cs:15:13:15:14 | f8 | LambdaAttributes.cs:15:17:15:52 | (...) => ... |
+| Func<int, string> | LambdaAttributes.cs:16:13:16:14 | f9 | LambdaAttributes.cs:16:17:16:60 | (...) => ... |
 lambdaDeclarationNatural
 | Func<bool, int> | Lambda.cs:16:13:16:14 | f5 | Lambda.cs:16:18:16:42 | (...) => ... |
 | Func<bool, object> | Lambda.cs:12:13:12:14 | f3 | Lambda.cs:12:18:12:47 | (...) => ... |
 | Func<bool, object> | Lambda.cs:17:13:17:14 | f6 | Lambda.cs:17:18:17:45 | (...) => ... |
 | Func<int, string> | Lambda.cs:9:13:9:14 | f2 | Lambda.cs:9:18:9:40 | (...) => ... |
+| Func<int, string> | LambdaAttributes.cs:14:13:14:14 | f7 | LambdaAttributes.cs:14:18:14:53 | (...) => ... |
+| Func<int, string> | LambdaAttributes.cs:15:13:15:14 | f8 | LambdaAttributes.cs:15:17:15:52 | (...) => ... |
+| Func<int, string> | LambdaAttributes.cs:16:13:16:14 | f9 | LambdaAttributes.cs:16:17:16:60 | (...) => ... |
 lambdaDeclarationExplicitReturnType
 | Func<bool, int> | int | int | Lambda.cs:16:13:16:14 | f5 | Lambda.cs:16:18:16:42 | (...) => ... |
 | Func<bool, object> | object | object | Lambda.cs:12:13:12:14 | f3 | Lambda.cs:12:18:12:47 | (...) => ... |