refactor(order/atoms): reorder arguments of `is_simple_lattice.fintype` (#8933)
refactor(order/atoms): reorder arguments of `is_simple_lattice.fintype` (#8933)

Previously, this instance would first look for `decidable_eq` instances and after that for `is_simple_lattice` instances. The latter has only 4 instances, while the former takes hundreds of steps. Reordering the arguments makes a lot of type-class searches fail a lot quicker.

Caught by the new linter (#8932).





leanprover-community/mathlib,leanprover-community/mathlib