[SYCL][SCLA] Add CodeGen capabilities for `sycl_ext_oneapi_private_alloca` #1344

Job	Run time
detect_changes / Decide which tests could be affected by the changes	6s
build / Build + LIT	49m 15s
Decide which Arc tests to run	1s
test-perf	0s
test (Intel, ["Linux", "gen12"], ghcr.io/intel/llvm/ubuntu2204_intel_drivers:latest, -u 1001 --de... / Intel	51m 34s
test (AMD/HIP, ["Linux", "amdgpu"], ghcr.io/intel/llvm/ubuntu2204_build:7ed894ab0acc8ff09262113fd... / AMD/HIP	12m 50s
test (E2E tests on Intel Arc A-Series Graphics, ["Linux", "arc"], ghcr.io/intel/llvm/ubuntu2204_i... / E2E tests on Intel Arc A-Series Graphics	1m 37s
	1h 55m 23s

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