RecoveryKeyResetPolicy

The host's policy for delayed recovery key resets (docs/recovery-key-reset.md): a reset requested at server time t can be completed from t + delay on (rounded up to whole milliseconds). The delay is the time every device of the user, and the holder of the current recovery key, has to notice and cancel a reset; choose it for how often the application checks. There is no default: a server without a policy refuses reset requests.