Implicit handling of verification room events and consequences

[BillCarsonFr]

Currently verification events are handled implicitely by the rust crate:
When decryption is called, if the decrypted event is a verification event it is then passed to the verification machine

Problem

If the client calls multiple decryptions it will have for effect that verifications events will be replayed, causing various failures on verifications.
One could say that client should avoid to retry decryption, but it could happen and nothing from API let you forsee the potential impact.

Also there is some asymmetry, where clear room verification events has to be passed manually to the olmMachine but not encrypted one

Proposed Solution

As per this comment, it would be better to have a single method that you need to call explicitly for every room verification event