C#: Add a test for compiler generated statements.

Author: michaelnebel

csharp/ql/test/library-tests/statements/CompilerGenerated.expected

@@ -0,0 +1,3 @@
+| fixed.cs:3:7:3:11 | {...} | fixed.cs:3:7:3:11 | Fixed |
+| statements.cs:7:11:7:15 | {...} | statements.cs:7:11:7:15 | Class |
+| statements.cs:243:15:243:25 | {...} | statements.cs:243:15:243:25 | AccountLock |

csharp/ql/test/library-tests/statements/CompilerGenerated.ql

@@ -0,0 +1,5 @@
+import csharp
+
+from Stmt stmt
+where stmt.isCompilerGenerated()
+select stmt, stmt.getEnclosingCallable()