Improve tests from example dir

[Chemaclass]

📚 Description

Related: #233

🔖 Changes

• Remove test make commands from example folder
• Split example folder into two
  • Testing a script with logic; you can save the script path during the setup, so you can "run" it on each test
  • Testing functions within a script; you have to load them using source

✅ To-do list

• I updated the CHANGELOG.md to reflect the new feature or fix
• I updated the documentation to reflect the changes