Add support for day types (enom, amrap, etc)

[rolandgeider]

At the moment the type field in Day (enom, amrap, etc) has no function, and can only be edited over the API. This should obviously change and be editable on web and mobile.

For mobile only: depending on the type, the gym mode should show the exercises in the right order / sequence. I'm not sure right now if we need some changes in the backend to shuffle the SetConfigDatas around or if we can do that in flutter. For some of these we will need to work with the timer etc so we will need to refactor that as well. We can ping Dieter, Hirequello and Aposthes on discord for details on how each should behave exactly (depending on the difficulty, we can start with the easy ones, will have to see).