C#: Add switch case expression type test

Author: tamasvajk

csharp/ql/test/library-tests/csharp8/switchCaseExprTypes.expected

@@ -0,0 +1,16 @@
+| patterns.cs:101:34:101:40 | "large" | Int32 |
+| patterns.cs:102:18:102:24 | "small" | Int32 |
+| patterns.cs:110:22:110:26 | (..., ...) | (Int32,Int32) |
+| patterns.cs:111:22:111:26 | (..., ...) | (Int32,Int32) |
+| patterns.cs:117:27:117:33 | (..., ...) | (Int32,Int32) |
+| patterns.cs:118:28:118:34 | (..., ...) | (Int32,Int32) |
+| patterns.cs:119:33:119:38 | (..., ...) | (Int32,Int32) |
+| patterns.cs:128:49:128:49 | 0 | MyStruct |
+| patterns.cs:129:38:129:38 | 1 | MyStruct |
+| patterns.cs:130:23:130:23 | 2 | MyStruct |
+| patterns.cs:131:27:131:27 | 3 | MyStruct |
+| patterns.cs:138:22:138:50 | throw ... | Object |
+| patterns.cs:139:22:139:22 | 3 | Object |
+| patterns.cs:140:42:140:42 | 4 | Object |
+| patterns.cs:141:29:141:29 | 5 | Object |
+| patterns.cs:142:41:142:41 | 6 | Object |

csharp/ql/test/library-tests/csharp8/switchCaseExprTypes.ql

@@ -0,0 +1,4 @@
+import csharp
+
+from SwitchCaseExpr case
+select case.getBody(), case.getType().toString()