Participation Key Interface

https://docs.google.com/document/d/1mQE_bQhkHKF-4Hn9WxcbD028_mwndR5G6g8mJgF8FZI/edit#heading=h.z1g0zy9rplhg

The current participation key management process could be improved. There are security and usability issues that can be solved to make it easier and safer to work with participation nodes. Specific problems that we’ll address:

1) Requires file system access to an algorand. This is a security flaw and leads to file permission problems. The design is tech debt that we have wanted to fix for a long time.
2) Because keys can appear at any time, algod checks for new keys every 60 seconds.
3) Limited insight into key usage details, requires log parsing.
4) Inconsistent behavior when an account has multiple key files registered with a node.
5) Updating the participation key file is slow.