Common Prep team and service lead #234

At the meal lead meetup we talked about different ways of wanting to organize our prep teams - and how this would be different on a per meal basis.

A feature request is to allow the meal lead to select how many meal prep and service lead people they want - for example:
one meal, the meal lead may choose assemble their own team so they do not need anyone to sign up as prep or service lead, so they would enter 0 in the box for number of meal prep and number of service leads.

Another meal might be prep intensive, in which case the meal lead might actually request 3 helpers for meal prep.

In the case of service leads, I think we should allow 0, 1, or 2 depending on the number of sittings.

This flexibility on a per-meal basis would support meal prep teams which is an idea that is forming, but also would support things working the way they are now, which works well for some meals and is a preference for some of the meal leads.

@rhogue Done! Two fields added in the meal form (see screenshot)

That said, I disabled these fields when updating an existing meal. Which means that, for now, we can't change the number of meal preps or service leads once the meal has been created in the system.

That will require a bit more work. So I'll keep this issue open to keep that on my radar.