Safe Dashboard: list of added Safes with extra info

[katspaugh]

Part of #3693.

Description

This is basically an extended version of the Safe sidebar. More compact and informative.

We'd like to display:

• All your added safes
• Each of which with:
  1. Address, name & identicon
  2. Threshold (e.g. 2/5)
  3. Total balance (fiat if possible, otherwise native coin)
  4. Link to open the Safe

Data source

The information for each Safe should come localStorage. So we'll display only previously added and loaded Safes.

The info may be outdated, but it's fine. It will refresh once the user opens that Safe.