Add negative tests for context API functions (#2494)

This PR adds negative tests for the following API functions:

- clCreateContext
- clCreateContextFromType
- clRetainContext
- clReleaseContext
- clSetContextDestructorCallback

Also, define a new macro `test_object_failure_ret` to test for an
expected error code and the returned object is `NULL` as a result of a
failure.

Signed-off-by: Michael Rizkalla <michael.rizkalla@arm.com>

test_conformance/api/CMakeLists.txt

@@ -6,6 +6,7 @@ set(${MODULE_NAME}_SOURCES
          main.cpp
          negative_platform.cpp
          negative_queue.cpp
+         negative_context.cpp
          negative_enqueue_marker.cpp
          negative_enqueue_map_image.cpp
          negative_device.cpp