Fruit Picker: Find (new) home for arrow functions concept

[junedev]

Because of #1725, the fruit picker concept exercise no longer includes tasks that require arrow functions. That means we need to find a (new) home for arrow functions. Here some options:

• A - Add a new concept exercise that teaches arrow functions
• B - Add arrow functions as a concept to one of the Elyses Enchantments exercises that teach array methods and heavily use arrow functions.
• C - Extend fruit picker to include tasks where arrow functions make sense and keep arrow functions as part of fruit picker

See also #1725 (comment) for more background.

[junedev]

I will work on this and go for option B for now.