cancelRecoveryKeyReset

Cancels the pending reset in one atomic step:

1. no reset is pending, or another one than RecoveryKeyResetCancellation.resetId: RecoveryKeyResetCancellationResult.NOT_PENDING;

2. the authority is no longer current (a device whose registration changed; a recovery key that is no longer the ACTIVE key at the reset's epoch): RecoveryKeyResetCancellationResult.CONFLICT;

3. removes the reset: RecoveryKeyResetCancellationResult.CANCELLED.

The recovery key state, its epoch and the challenges never change. No record of the cancellation is kept.