Illegal parameters and libspdm_requester_*_test_*_message

[steven-bellock]

When testing illegal parameters on public Requester functions libspdm_requester_*_test_send_message and libspdm_requester_*_test_receive_message usually returns LIBSPDM_STATUS_SUCCESS for that case. However this is misleading as libspdm_requester_*_test_*_message should not be called for that case and it should be considered an implementation bug if it is called. For example

libspdm/unit_test/test_spdm_requester/error_test/get_measurements_err.c

Lines 3238 to 3241 in 4b0a3c5

	/**
	* Test 9: Integrator requests signature when Responder does not support signatures.
	* Expected Behavior: Returns LIBSPDM_STATUS_INVALID_PARAMETER.
	**/

and

libspdm/unit_test/test_spdm_requester/error_test/get_measurements_err.c

Lines 148 to 149 in 4b0a3c5

	case 0x9:
	return LIBSPDM_STATUS_SUCCESS;

cmocka's assert_true(false); should be hit before returning from the function.