Add Lua Gnome template

Add a template that helps to get started with Gtk, Adwaita, Lua, Meson, Localization, Flatpak and ability to run in Gnome Builder. This will be a huge help for newcomers.
See https://gitlab.gnome.org/World/Rust/gtk-rust-template/, https://github.com/flattool/typescript-app-template, https://gitlab.gnome.org/monster/pygobject-template