Function std::url_encode_path

struct String url_encode_path(const &char s)

Like url_encode, but keeps the characters a URL path may hold as-is: '/', and RFC 3986's sub-delims and ':' '@' (so "/a b/c:d" becomes "/a%20b/c:d"). '%' itself is always escaped, so this is not idempotent — encode raw paths, not already-encoded ones.