std::string_view is stringified without quotes

[melak47]

Description

std::string_view probably uses some fallback stringification, and is expanded without quotes (and also bypasses pretty printing of invisibles).

Steps to reproduce

#define CATCH_CONFIG_MAIN
#include <catch2/catch.hpp>

#include <string>
#include <string_view>

TEST_CASE("string_view == string") {
    std::string s = "foo";
    std::string_view v = s;

    CHECK(s == v);
}

run with -s:

PASSED:
  CHECK( s == v )
with expansion:
  "foo" == foo

Extra information

Catch version: v2.4.0