Structured JSON export of rated wallet data

[polymutex]

We should provide JSON exports of fully-rated wallet data.

The wallet data in /data/wallets is good but only covers feature data. A full RatedWallet JSON export would include this, but also all the attribute rating data, rationale for why each attribute has each rating, etc.

Another difference is that it would also be fully expanded across wallet variants (mobile/desktop/etc) and would have no helper functions, whereas the data in /data/wallets is optimized for human readability/terseness/ease of filling out. The fully-expanded JSON blob is for machine consumption, so verbosity isn't as much of an issue.