Added a gidpod config and updated readme.MD to show gitpod button

Added a .gitpod.yml

Other changes

• Added a Gitpod Deploy Button in the README.MD file.
• Adjusted package.json to clear only the content and not removes the assets folder.
• Added Xdebug for PHP.
• Added CURRENT_USER environment variable to all DEV-scripts.
• Added CURRENT_USER environment variable to the required Docker containers (client, chat) which should run as non-ROOT (user: ${CURRENT_USER}).
• Reduced the duplicates in the seed data.

These commands should work

• ./scripts/start && ./scripts/seed and runs as init
• ./scripts/test
• ./scripts/clean

Testing

BE AWARE permission errors are possible, when testing locally (To solve this run git clean -fdX).

• Does it work locally?
• Does it work in Gitpod? → https://gitpod.io/#https://gitlab.com/foodsharing-dev/foodsharing/-/merge_requests/2386

Knowing bugs

• rare case, Warning: file_put_contents(/app/var/cache/dev/annotations.map): Failed to open stream: Permission denied – rerun ./scripts/start
• client/node_modules is still a root folder (docker volume) but CURRENT_USER should be able to remove it
• chat/node_modules is still a root folder (docker volume) but CURRENT_USER should be able to remove it