Refactor Shared networks table

This is a follow-up ticket of #1433 (closed).

To limit the size of MR !806 (merged), refactoring of the Shared Networks table will be tackled here.

The goal is to refactor the table as it was done with Host Reservations and Subnets tables. The table becomes a separate component with a unified look and feel (many filtering bugs were fixed thanks to that).