[NFC][SYCL] Refactor OSUtils to use std::filesystem

[uditagarwal97]

For older gcc versions (< 8), use std::experimental::filesystem.

[KseniyaTikhomirova]

is
"#if defined(__has_include) && __has_include()" really false for old gcc?
would it be better to use feature test macro? https://en.cppreference.com/w/cpp/feature_test#cpp_lib_filesystem

[uditagarwal97]

is
"#if defined(__has_include) && __has_include()" really false for old gcc?

Yes: https://godbolt.org/z/Wf3oMGMeG

would it be better to use feature test macro? https://en.cppreference.com/w/cpp/feature_test#cpp_lib_filesystem

I think we can not use feature test macro here. Because, cpp doc says:

Unlike the language feature test macros, they are not predefined. Instead, they are provided by the header <version>

For each library feature test macro, it is also provided by the headers that provide the relevant standard library components.

<version> header is available post C++ 20, so IIUC, it is not available with older compilers: https://en.cppreference.com/w/cpp/header/version