Stop using std::is_trivial

[akukanov]

Since std::is_trivial is deprecated in C++ 26, it makes sense to get rid of it in our code in advance. This is requested in the issue #1961.

In type_traits, we simply inject names into the oneDPL namespace, so the only change there so far is to add a comment.

In glue_memory_impl,h, is_trivial is checked to "optimize" the implementation for trivial types (it is worth checking if that really brings any performance improvement, but let's keep that for later). There we have a few cases:

• In uninitialized_copy/move, the in-place construction is changed to the "copy" brick, which essentially does an assignment like *result = *input. Therefore, here the check is for the result value type to be trivially default-constructible and trivially assignable from the input reference type.
• In uninitialized_value_construct, the "optimization" uses the "fill" brick which assigns a given value of the output value type. Therefore the new check is for trivially default-constructible and trivially copyable. The same logic applies to uninitialized_fill, which currently (before the patch) checks for std::is_arithmetic :)
• In uninitialized_default_construct, construction is fully skipped - so the check should be for trivially default-constructible only.

Update: In a discussion with @rarutyun we come to the conclusion that the triviality of both expected and actual operations should be checked in the condition. The patch is updated accordingly.

[rarutyun]

Looks good to me assuming the clang-format makes things worse and we want to ignore it for this patch

[akukanov]

Thanks.
In my opinion, soothing clang-format would make things slightly worse; this is one kind of subjective formatting preferences which are tolerable either way. So, if someone insists, I will "fix" it, otherwise will leave as is.