Allow adding protocols to watchlist via protocol view

[0xmichalis]

The only way to add a protocol to the watchlist currently is to find it in its own category and click the flag next to it.

It would be nice to be able to add to watchlist directly via the protocol view. A couple of options I can think of:

1. add the flag icon next to the protocol logo, or
2. add a "Add to Watchlist" checkbox with the rest of the checkboxes