Integration of Mithril/DMQ nodes with Cardano node

## Why

With #2524, we have outlined proposals to drive greater adoption of Mithril signers among SPOs. We plan is to integrate Mithril into the official SPO documentation and include the Mithril signer and DMQ node binaries in the official Cardano node release on GitHub.

There is a chicken and egg problem with the creation of the Mithril distribution:
- It currenlty needs the Cardano node pre-release to prepare support for it
- Including Mithril signer binary requires to have a Mithril distribution pre-release ready before the Cardano pre-release is created

This means that we need to modify our release process so that it can allow the preparation of a pre-release prior to the creation of the Cradano pre-release.

## What

Evolve the Mithril nodes release process and documentation to support closer integration with Cardano.

## How
- [x] #3012
- [x] #2989
- [x] #3011
- [x] https://github.com/IntersectMBO/dmq-node/issues/21
- [x] #3058
- [x] #3070