Lua README

When updating the Lua submodule to a new major/minor version (e.g. 5.4 to 5.5), please also update the system Lua checks in the build systems and CI.

Download new versions of https://gitlab.kitware.com/cmake/cmake/-/raw/master/Modules/FindPackageMessage.cmake and https://gitlab.kitware.com/cmake/cmake/-/raw/master/Modules/FindPackageHandleStandardArgs.cmake to cmake/.

Update cmake/FindLua.cmake from https://gitlab.kitware.com/cmake/cmake/-/raw/master/Modules/FindLua.cmake and cherry pick the Wesnoth commit "Modify FindLua.cmake to find Lua compiled as C++".

In CMakeLists.txt, update set(Lua_FIND_VERSION_MAJOR 5) and set(Lua_FIND_VERSION_MINOR 4). In SConstruct, update lua_ver = "5.4".

In .github/workflows/codeql.yml and utils/dockerbuilds/CI/Dockerfile-base-2204-master, update liblua5.4-dev.