Add recovery fallback for secrets.json file

[brentru]

Sometimes the secrets.json is either deleted (accidentally) or corrupted. Instead of this, @tyeth and I were discussing a way to store, on boot, the secrets.json's content in-memory and persist it through boot cycles.

On boot, the device would:

1. check for the existence of this content, recover it and place into a new secrets.json file on the FS
2. create a new secrets.json file (current operation)

We'd need to:

• Profile the secret.json max. possible size
• Consider using a struct or just a string depending on serialization/deserialization difficulty.