chore(*): add mathlib4 synchronization comments (#18333)
Regenerated from the [port status wiki page](https://github.com/leanprover-community/mathlib/wiki/mathlib4-port-status).
Relates to the following files:
* `algebra.big_operators.finsupp`
* `algebra.direct_sum.basic`
* `algebra.is_prime_pow`
* `combinatorics.set_family.shadow`
* `data.dfinsupp.ne_locus`
* `data.finsupp.fintype`
* `data.finsupp.ne_locus`
* `data.fun_like.fintype`
* `group_theory.group_action.sub_mul_action.pointwise`
* `group_theory.monoid_localization`
* `group_theory.subgroup.finite`
* `order.filter.modeq`
* `order.filter.pointwise`
* `ring_theory.subsemiring.basic`
