[SYCL] persistent cache fix - directory creation and reporting improvements

[cperkinsintel]

We have a report of persistent cache failures. Traced to the directory creation so I switched it to use C++17 std::filesystem routines for OSUtil::makeDir. Also improved trace reporting.

[AlexeySachkov]

Even though I'm ok to merge this patch, because it improves error reporting, which is very helpful for debugging and it does not make a situation worse, whilst being a very small fix.

I don't think that it fully resolves all the problems we have:

• using files for thread-safety doesn't seem to work, at least not in our implementation. There should either be an in-memory atomic lock, or we should have a wait loop to further iterate on i on a failed attempt to acquire a lock
• we ignore any "extra" device images, i.e. our hash collision mechanism doesn't work

different direction

[sergey-semenov]

LGTM overall

[sergey-semenov]

Should we throw in this case as well, to align the two branches?

[cperkinsintel]

changing the signature of this function leads to an ABI break. Since we need to keep this old stuff anyway, I was thinking to keep it as is.
My preference would be to change the signature, throw always, and drop GCC < 8 support, but that decision isn't mine to make.

[sergey-semenov]

We can keep the signature as is and still throw when we would have returned a non-zero code. I don't think we're handling non-zero codes returned from this anyway, are we?

[cperkinsintel]

std::fileystem::create_directories throws a std::filesystem::filesystem_error but the "old" code doesn't have std::filesystem so can't throw that. I'm modifying it to throw std::runtime_error