[SYCL] Add "ext_oneapi_offload" backend enum value #20421

Job	Run time
detect_changes / Decide which tests could be affected by the changes	7s
build / Build + LIT	26m 28s
build_ubuntu2204	0s
run_prebuilt_e2e_tests (Dev IGC on Intel Ponte Vecchio GPU, ["Linux", "pvc"], ghcr.io/intel/llvm/... / Dev IGC on Intel Ponte Vecchio GPU	5m 54s
run_prebuilt_e2e_tests (GEN 12 Integrated, ["Linux", "gen12"], -u 1001 --device=/dev/dri -v /dev/... / GEN 12 Integrated	11m 19s
run_prebuilt_e2e_tests (Intel Battlemage Graphics, ["Linux", "bmg"], -u 1001 --device=/dev/dri -v... / Intel Battlemage Graphics	4m 22s
run_prebuilt_e2e_tests (SPIR-V Backend / Intel Battlemage Graphics, ["Linux", "bmg"], -u 1001 --d... / SPIR-V Backend / Intel Battlemage Graphics	4m 30s
run_prebuilt_e2e_tests (E2E tests with dev igc on Intel Arc A-Series Graphics, ["Linux", "arc"], ... / E2E tests with dev igc on Intel Arc A-Series Graphics	4m 19s
run_prebuilt_e2e_tests (AMD/HIP, ["Linux", "amdgpu"], -u 1001 --device=/dev/dri --device=/dev/kfd... / AMD/HIP	9m 34s
run_prebuilt_e2e_tests (E2E tests on Intel Ponte Vecchio GPU, ["Linux", "pvc"], -u 1001 --device=... / E2E tests on Intel Ponte Vecchio GPU	6m 56s
run_prebuilt_e2e_tests (Intel Arc A-Series Graphics, ["Linux", "arc"], -u 1001 --device=/dev/dri ... / Intel Arc A-Series Graphics	5m 59s
run_prebuilt_e2e_tests (NVIDIA/CUDA, ["Linux", "cuda"], -u 1001 --gpus all --cap-add SYS_ADMIN, c... / NVIDIA/CUDA	4m 45s
test-perf	0s
	1h 24m 13s

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