[SYCL][CUDA] Set PI_CUDA_ENABLE_IMAGE_SUPPORT before running Image tests (intel/llvm-test-suite#702)

This allows to run Image tests currently supported by the CUDA BE
even if the Image support is disabled by default.

This follows intel#5256

Author: pgorlani

SYCL/lit.cfg.py

@@ -310,6 +310,9 @@
         gpu_run_on_linux_substitute = "env SYCL_DEVICE_FILTER={SYCL_PLUGIN}:gpu,host ".format(SYCL_PLUGIN=config.sycl_be)
         gpu_check_on_linux_substitute = "| FileCheck %s"
 
+    if config.sycl_be == "cuda":
+        gpu_run_substitute += "SYCL_PI_CUDA_ENABLE_IMAGE_SUPPORT=1 "
+
 else:
     lit_config.warning("GPU device not used")