Add composer.json

Add composer.json, following best practices for TYPO3 Projects.

Relates: #5
3 jobs for feature/5-add-composer-json in 1 minute and 31 seconds
Status Name Job ID Coverage
  Lint
passed lint:composer #19414

00:00:16

 
  Setup
passed setup:composer #19416

00:01:15

passed setup:composer #19415

00:01:18