refactor(order/bounds,*): move code around to make `order.bounds` not depend on `complete_lattice` (#1783)
* refactor(order/bounds,*): move code around to make `order.bounds` not depend on `complete_lattice`
In another PR I'm going to prove more facts in `order/bounds`, then
replace many proofs of lemmas about `(c)Sup`/`(c)Inf` with references to lemmas
about `is_lub`/`is_glb`.
* Move more code to `basic`, rewrite the only remaining proof in `default`
* Rename
* Add `default.lean`