Improve User Management capabilities for Product Owners

Product Line owners (Product Owners of Product Lines) need to have better mechanisms to manage their users (especially for cases where the Product Line has several lower level product lines & products).

Ideally, Product Owners should have the following visibility and capabilities in the Users Page:

1. Have the possibility to see the users' access to the product line and all its children (if a product line owner owns 20 products, it is not realistic to go one by one over all of them).

2. Have filtering capability, so that they can see Product Owners and Contributors only if desired, or everybody. Or have the possibility to filter by a set of products in the product line, instead of all.

3. Be able to export that data for analysis purposes.

4. Have the possibility to see when was the last time that the user has logged in or how long ago.

We understand that Admins can do this in Billing/Users Admin section, BUT Product Owners should be able to do it too, without needing to have Admin access.