EXSWHTEC-315 - Implement unit tests for dim3 (#298)

- Implement unit tests for dim3
- Add doxygen comments

catch/include/hip_test_defgroups.hh

@@ -36,6 +36,13 @@ THE SOFTWARE.
  * @}
  */
 
+/**
+ * @defgroup VectorTypeTest Vector types
+ * @{
+ * This section describes tests for the Vector type functions and operators.
+ * @}
+ */
+
 /**
  * @defgroup DeviceTest Device Management
  * @{