View source for cpp/ranges/split view

===Notes===
Before {{wg21|P2210R2}}, {{tt|split_view}} used a ''lazy'' mechanism for splitting, and thus could not keep the bidirectional, random access, or contiguous properties of the underlying view, or make the iterator type of the inner range same as that of the underlying view. Consequently, it is redesigned by {{wg21|P2210R2}}, and the lazy mechanism is moved to {{rlpt|lazy_split_view}}.

The delimiter {{tt|pattern}} generally should not be an ordinary string literal, as it will consider the null terminator to be necessary part of the delimiter; therefore, it is advisable to use a {{lc|std::string_view}} literal instead.