Define a protocol for detail feed table's data source

This protocol essentially wraps two existing protocols
provided by UIKit: UITableViewDataSource and
UITableViewDelegate. In addition, it also defines one
required method and one optional method.
Provide a default impl of detail feed table data source protocol
Create a custom table view cell to show detail feed info
Create a VC that manages detail feed table view
Push detail feed VC into navigation stack

When a feed card is tapped from the list view,
we show the detail info for that feed using an
instance of FeedDetailViewController class.