feat: add Zig examples ⚡

[elsantiF]

This Pull Request add Zig examples of the projects. It's using Zig 0.16.0.

[joaquinlarroca]

Could you change the folder distribution so it matches

language/
├── 01_hello_world/
├── 02_calculator/
├── 03_number_guessing_game/
├── 04_todo_list/
├── 05_palindrome_checker/
├── 06_fizzbuzz/

Basically dividing each challenge into its own zig project/codebase