Update gsl-lite

[cagelight]

The ancient version of gsl-lite currently on the repo does not compile on modern setups, so I have updated the gsl-lite file and taken care of all of the things that have been renamed since the older file. Seemed like just a mass find/replace operation more or less.

[MichaelColonel]

I've tested this PR on Linux, both Outcast and Academy single player, Release build with gcc-13.2. No problems with compilation and execution.

Before this PR most of gsl-lite errors on Linux ,in my case, were because of undefined std namespace within gsl namespace.

Simple fix for me was to replace std:: to ::std::.
For example:
std::reverse_iterator< iterator > reverse_iterator; -> ::std::reverse_iterator< iterator > reverse_iterator;

[bartrpe]

Gave it a test on Debian 12.1 with the newest GCC version and didn't encounter any errors building.

[Daggolin]

Gave it a test on Debian 12.1 with the newest GCC version and didn't encounter any errors building.

As far as I know Debian 12 is still on gcc 12. Using gcc12 works for me on the current master branch. Using gcc13 or clang16 did not. With this pull request they work as well.

The sha256sum of lib/gsl-lite/include/gsl/gsl-lite.h matches the current https://raw.githubusercontent.com/gsl-lite/gsl-lite/master/include/gsl/gsl-lite.hpp, so it seems to still be the latest version.

Seems like most of the changes replace cstring_view with cstring_span, because cstring_view seems to have been renamed to cstring_span back in 2015.