improve coin selection

[jorian]

Describe the feature

In the Settings section, the amount of available coins that are available is confusing for the user. Most coins will initially not be traded by many users. We should rethink how we can make selecting active coins easier.

simple solution
There should be a split section in the list of available coins: first coins that are in the top 10-15 of CoinMarketCap, including KMD, then a section of all KMD assets that exist in the ecosystem, and then a list of all other coins.

overhaul
We can also opt for a new separate, overlaying screen, where there is more space to show coins, as well as different sections of coins (KMD assets, ERC20 tokens etc.).