D8 Port coding standards and logic issues

Please note, there were a lot of Coding Standard issues in my patch in #2821493 which I fixed right away ... plus some logical issues I found.

But let me add an other patch here, so you can see the difference:

• Coding Standard Fixes
• Documentation Fixes
• Missing token service
• undefined variable
• Handler not instanciated
• #dependencies vs. #states in Form API
• .module file not required
• remove unused use statements

As requested, I opened a new ticket.