Setup composer

Issue: #18

Setup composer with PSR-4 to class autoload

[ ] fix: A bug fix
[ ] feat: A new feature
[ ] refactor: A code change that neither fixes a bug nor adds a feature
[ ] enhancement: An enhancement makes something better
[ ] test: Adding missing tests or correcting existing tests
[ ] perf: A code change that improves performance
[ ] docs: Documentation only changes
[ ] style: Changes that do not affect the meaning of the code (e.g. prettier format)
[ ] ci: Changes to our CI configuration files and scripts
[x] chore: Changes to the build process or auxiliary tools and libraries functionality to not work as expected

Hours Required: 1

yuutokolanz / backend-lesson-problem-track