Also renames lua/lua.hpp to lua/lua_global.hpp.
The previous name broke version auto-detection in sol2, which involves
calling `__has_include(<lua/lua.hpp>)`.
On CMake v3.28+, `EXCLUDE_FROM_ALL` is supported natively as an argument
to `FetchContent_Declare`.
On CMake v3.30+, `FetchContent_Populate`, which we use to polyfill
`EXCLUDE_FROM_ALL` support for older versions of CMake, is deprecated
and triggers a noisy warning.
Avoids the warning by using the native `EXCLUDE_FROM_ALL` support on
CMake v3.28+.
Chris V.
Anders Jenbo
Gleb Mazovetskiy
staphen