feat(order/bounded_lattice): unbot and untop (#8885)
feat(order/bounded_lattice): unbot and untop (#8885)

`unbot` sends non-`⊥` elements of `with_bot α` to the corresponding element of `α`. `untop` does the analogous thing for `with_top`.





leanprover-community/mathlib,leanprover-community/mathlib