Allow piggybacking of formula fields

There are many use cases when it would be preferable to be able to, within an object, create a formula field off a formula field.

There are two reasons for this:

1. It is burdensome to have to test multiple formulas in depth and sometimes one formula is part of another
2. The UI isn’t super friendly for formula building- it is tedious to get everything to line up as expected and sometimes takes multiple tries; this would allow for shorter formulas