[SYCL] adding binary caching support to kernel_compiler extension

[cperkinsintel]

Trying to reuse as much of the PersistentDeviceCodeCache as possible. We use the same top cache directory as the regular binary caches, but with a ext_kernel_compiler subdirectory and a slightly different system for assigning paths.

Rather than write new tests, am just adding a "test the cache" passes to the existing tests.

[cperkinsintel]

The Jenkins/Precommit failure seems to be unrelated. Several other PRs are having the RHEL Build fail and a quick test seems to suggest it is a UR dependency problem.

[steffenlarsen]

LGTM!

[againull]

@cperkinsintel Could you please take a look at post-commit failure on gen12 and arc:

---

Failed Tests (1):
SYCL :: KernelCompiler/kernel_compiler_sycl.cpp

https://github.com/intel/llvm/actions/runs/11634776354/job/32403188036
https://github.com/intel/llvm/actions/runs/11634776354/job/32403188263

[sarnex]

@cperkinsintel Does it seem like an easy fix? If not we might want to disable the test or revert the change. Thanks