Cardano Updates

- Previously we assummed each new broadcasted message index was n + 1
and now we take the message index from the acks we constructed.

If Alice is lagging behind Bob and Bob is lagging behind Alice then
nobody would resend any message to its peer.

Here we remove one condition to unlock this.

If Alice is lagging behind Bob and Bob is lagging behind Alice then
nobody would resend any message to its peer.

Here we remove one condition to unlock this.

Make hydra-cluster --devnet open a head

- We want to be able to connect using hydra-tui thus need the
location of generated key.

This may become handy when doing integration tests with indexers or as a
development sandbox.

Updated security policy and vulnerability disclosure policy

Bug was exposed by running:
```
cabal test hydra-node --test-options '-m Reliability --seed 1054015251'
```

The problem was caused by Bob increasing his local view of received
messsages from Alice from 15 to 16 when receiving a Ping from Alice
when, actually, he never received this message 16 before.

As a consequence, Alice would not resend message 16 or, when she
resends message 16, Bob would ignore it anyway as it's expecting
:x

At least not fast enough compared to the time we were giving their
messages to arrive.

Sending a message once every ten seconds and expecting all the
messages to reach the peer in less than 100 seconds does not
always work.

- We want to be able to connect using hydra-tui thus need the
location of generated key.

Co-authored-by: Pascal Grange <[email protected]>