Honestly I have never been a fan of separating the datasource/delegate methods in to separate classes or extensions. I think in the end you end up writing more code and making the project more complicated/convoluted than it really needs to be.
If your code for this table needs to be modular/reusable, then simply make the UITableView/collection view itself a separate class, and put the code in that subclass. That way, all you need to do to reuse this view is to use this subclass