[Feature Request] [Longterm] Replace const-ref std::string arg with std::string_view

[elad335]

The difference between the two is that reference references an object of type std::string which is defined to contain a unique buffer for its characters, while std::string_view describes a section of existing memory containing the characters. The previous arguments decleration style makes passing substring and static C-string to a function include an additional and (99% of the time) unneccessary step of allocating new buffer for and copying the characters to it, std::string_view argument does not have this flaw as it is capable of describing these sections of memory without copying them.

[elad335]

This is true for even static constexpr std::string in C++20 when an address is required such as when calling c_str() (compiler cannot optimize it, buffer must be unique in this case). So string_view is recommended for static strings as well.

[Nekotekina]

For constexpr strings plain old char array can do its job. It's usually not a problem to convert it to string_view on the fly. It feels however we may be missing some kind of nts_view to preserve a null-terminator.