Adding makefile and composer/console autocompletion for a smooth discovering workflow

This PR provides

A makefile following the example of https://github.com/jorge07/symfony-5-es-cqrs-boilerplate/blob/symfony-5/makefile to provide a smooth workflow while discovering Ecotone.
Adds /data/app/bin to $PATH so console is instantly available
Applies chown 1000:1000 to all the vendor directory to avoid blocking due to failing chown on unfound /vendor/composer
It also adds bash-completion and autocomplete for Symfony's console and composer to discover Ecotone available commands fastly
An updated README to get this workflow easily

My main concern here is about dev vs production docker images and behavior in a Kubernetes environment (which I personally never used).

Hoping you will find it interesting!

Anyway, thank you for your inspiring work and open-sourcing it

ecotoneframework / php-ddd-cqrs-event-sourcing-symfony-laravel-ecotone