Support Offering Variants

[bcholmes]

Some offerings should be available as variants: e.g. T-shirts (S, M, L, XL, 2X, etc.), at-day memberships (Fri, Sat, Sun, Mon), etc. Variants can have distinct pricing (Friday at-con membership is generally cheaper than Sat or Sun).

Arguably, even memberships can be variants (Adult, Teen, Youth, etc.)

[bcholmes]

Some thoughts:

• this feature can help reduce the number of items on the main "offering" page. Rather than have 3 different "Donation" options, for example, we can have one option for donation, and select a "where should the funds go" destination as a variant. That helps make the main page less overwhelming.
• we should probably think about cases where someone wants to change their variant. If we used "in-person" and "online" as variants, for example, we need to think about the case where someone wants to change from one to the other. (In the cases were the options cost the same, that's relatively easy.)
• Different variants might have different costs. But when we show the offering on the main page, we may want to emphasize the "most likely" cost, rather than, say, the smallest cost. E.g. if Adult in-person memberships are $65 and online memberships are $35, is it possible that we'll want to show the price on the first page as "$65 +/-" or "$35+"? Or just "varies"? I feel like the most common option should be shown.

[bcholmes]

One additional thought: we definitely want to show the variant in the report.