chore(topology/*): use dot syntax for some lemmas (#3251)
Rename:
* `closure_eq_of_is_closed` to `is_closed.closure_eq`;
* `closed_of_compact` to `compact.is_closed`;
* `bdd_above_of_compact` to `compact.bdd_above`;
* `bdd_below_of_compact` to `compact.bdd_below`.
* `is_complete_of_is_closed` to `is_closed.is_complete`
* `is_closed_of_is_complete` to `is_complete.is_closed`
* `is_closed_iff_nhds` to `is_closed_iff_cluster_pt`
* `closure_subset_iff_subset_of_is_closed` to `is_closed.closure_subset_iff`
Add:
* `closure_closed_ball` (`@[simp]` lemma)
* `is_closed.closure_subset : is_closed s → closure s ⊆ s`
