C#: Add pointer cast test cases

csharp/ql/test/library-tests/conversion/pointer/Pointer.cs

@@ -0,0 +1,28 @@
+using System;
+
+class C
+{
+    unsafe static void M1(int[] arr)
+    {
+        fixed (int* i1 = arr)
+        {
+        }
+
+        fixed (int* i2 = &arr[0])
+        {
+            int* i3 = i2;
+            i3 = i3 + 1;
+            *i2 = *i2 + 1;
+            void* v2 = i2;
+        }
+
+        int* i4 = null;
+
+        int number = 1024;
+        byte* p = (byte*)&number;
+
+        var s = "some string";
+        fixed (char* c1 = s)
+        { }
+    }
+}

csharp/ql/test/library-tests/conversion/pointer/Pointer.expected

@@ -0,0 +1,11 @@
+| Pointer.cs:7:21:7:28 | Pointer.cs:7:21:7:28 | Int32* | Int32[] | access to parameter arr |
+| Pointer.cs:11:21:11:32 | Pointer.cs:11:21:11:32 | Int32* | Int32* | &... |
+| Pointer.cs:13:18:13:24 | Pointer.cs:13:18:13:24 | Int32* | Int32* | access to local variable i2 |
+| Pointer.cs:14:13:14:23 | Pointer.cs:14:13:14:23 | Int32* | Int32* | ... + ... |
+| Pointer.cs:15:13:15:25 | Pointer.cs:15:13:15:25 | Int32 | Int32 | ... + ... |
+| Pointer.cs:16:19:16:25 | Pointer.cs:16:19:16:25 | Void* | Void* | (...) ... |
+| Pointer.cs:19:14:19:22 | Pointer.cs:19:14:19:22 | Int32* | null | null |
+| Pointer.cs:21:13:21:25 | Pointer.cs:21:13:21:25 | Int32 | Int32 | 1024 |
+| Pointer.cs:22:15:22:32 | Pointer.cs:22:15:22:32 | Byte* | Byte* | (...) ... |
+| Pointer.cs:24:13:24:29 | Pointer.cs:24:13:24:29 | String | String | "some string" |
+| Pointer.cs:25:22:25:27 | Pointer.cs:25:22:25:27 | Char* | String | access to local variable s |

csharp/ql/test/library-tests/conversion/pointer/Pointer.ql

@@ -0,0 +1,5 @@
+import csharp
+
+from Assignment a
+select a.getLocation(), a.getLValue().getType().toString(), a.getRValue().getType().toString(),
+  a.getRValue().toString()