chore(*): add mathlib4 synchronization comments (#18443)
Regenerated from the [port status wiki page](https://github.com/leanprover-community/mathlib/wiki/mathlib4-port-status).
Relates to the following files:
* `algebra.module.submodule.pointwise`
* `category_theory.comma`
* `category_theory.products.associator`
* `category_theory.products.basic`
* `category_theory.products.bifunctor`
* `combinatorics.partition`
* `data.finsupp.lex`
* `data.nat.count`
* `data.nat.periodic`
* `group_theory.index`
* `linear_algebra.pi`
* `linear_algebra.span`
* `number_theory.ADE_inequality`
* `topology.algebra.monoid`
* `topology.sets.compacts`
* `topology.uniform_space.compact_convergence`
