Use std::string_view instead of strlen

[ltrk2]

I used std::string_view instead of statically allocated const char* in order to save a call to strlen and make things look more modern.

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• Not for changelog (changelog entry is not required)

[alexey-milovidov]

There is no call to strlen. The code is written in a way that the strlen result is known at compile time.

[alexey-milovidov]

Nevertheless, the change is ok.