EXSWHTEC-304 - Expand and refactor tests for clock device functions (#273)

- Expand and refactor clock device functions
- Add comments and format code
- Fix doxygen test group comments

catch/include/hip_test_defgroups.hh

@@ -135,3 +135,9 @@ THE SOFTWARE.
  * This section describes tests for the Device Language API.
  * @}
  */
+
+/**
+ * @defgroup DeviceLanguageTest Device Language
+ * @{
+ * This section describes tests for the Device Language API.
+ */