Implement Moodle Coding Guidelines

[lucaboesch]

I had some fun and learned about fixing coding guidelines with phpcbf commands. So, I played around with the choicegroup code base and fixed some stuff, not touching anything related to logic or tests, just basic things. I left the JavaScript untouched. I did not fix the update savepoints problems.

Feel free to peer review, and, if to your liking, merge.

Best, Luca

[ndunand]

Thanks @lucaboesch ,

Again for offering your time and work 😊

I reviewed the code and all looks good. I have also tested and hove someone else testing more extensively to make sur there are no unforeseen regressions or surprises.

I'll merge afterwards