Build using Zig toolchain from within Godot editor for Windows 11

[fire]

The Zig toolchain is an optional feature in godot-sandbox allowing you to build complex projects with dependencies from within the Godot editor.

1. Install scoop install git cmake ninja zig

Require zig greater than or equal to 0.13 version. Zig 0.14 reduces binary size a lot.

2. Make a cmake folder in the project root exactly res://cmake
3. Add file res://cmake/.gdignore to ignore the contents.
4. Add res://cmake/CMakeLists.txt

cmake_minimum_required(VERSION 3.14)
project(example)

include(FetchContent)
FetchContent_Declare(
    godot-sandbox
    GIT_REPOSITORY https://github.com/libriscv/godot-sandbox.git
    GIT_TAG        main
    SOURCE_SUBDIR  "program/cpp/cmake"
)
FetchContent_MakeAvailable(godot-sandbox)

set(PROOT ${CMAKE_SOURCE_DIR}/..)

add_sandbox_program_at(player ${PROOT}/scenes/player.elf
    ${PROOT}/scenes/player/player.cpp
)

5. Copy toolchain.cmake from Godot Sandbox Programs repo to res://cmake/toolchain.cmake

Also, copy the remaining scripts from the cmake folder into res://cmake/cmake so that you now have:
- res://cmake/cmake/zig-ar.cmd
- res://cmake/cmake/zig-ranlib.cmd

6. Initialize CMake with the toolchain file as an argument. The toolchain file is only used to initialize CMake, which is the same on all platforms. You can put this code snippet in cmake\build.cmd:

set HERE=%cd%
mkdir .build
pushd .build
cmake .. -G Ninja -DCMAKE_BUILD_TYPE=Release -DSTRIPPED=ON -DCMAKE_TOOLCHAIN_FILE=%HERE%\toolchain.cmake
cmake --build .
popd

The example CMake script looks for player.cpp and builds player.elf. It supports full C++ API and Godot run-time API.

7. Hero wanted: Add an integration to setup/configure cmake automatically from godot-sandbox
   CMake is already automatically called once it has been configured from the Godot editor. Try saving a C++ file in the editor, and you will see that it only uses CMake instead of other methods.