chore(*): add mathlib4 synchronization comments (#18283)
Regenerated from the [port status wiki page](https://github.com/leanprover-community/mathlib/wiki/mathlib4-port-status).
Relates to the following files:
* `algebra.ring.fin`
* `control.functor.multivariate`
* `data.fin.tuple.sort`
* `data.lazy_list.basic`
* `data.set.countable`
* `data.set.equitable`
* `data.set.intervals.infinite`
* `data.set.intervals.instances`
* `order.filter.archimedean`
* `order.filter.at_top_bot`
* `order.filter.bases`
* `order.filter.cofinite`
* `order.filter.countable_Inter`
* `order.filter.indicator_function`
* `order.filter.lift`
* `order.filter.n_ary`
* `order.filter.pi`
* `order.filter.small_sets`
* `order.filter.ultrafilter`
* `order.order_iso_nat`
