spin-up a fork-observer instance in the warnet docker-compose

[0xB10C]

The fork-observer tool visualizes the header tree of multiple nodes and which header/blocks nodes consider to be active/stale. This allows tracking forks and reorgs. For warnet, it could also highlight stuck nodes. A live version of fork-observer is available on https://fork.observer.

While the tool is still work-in-progress, I think it makes sense to have the option to spin up an instance along side the Bitcoin nodes and the grafana dashboard. The the configuration file for fork-observer can be generated from the XML file with the node information.

[0xB10C]

As a first step, it might make sense to add a fork-observer CI job that builds a docker-image and pushes it to some registry.

[willcl-ark]

As a first step, it might make sense to add a fork-observer CI job that builds a docker-image and pushes it to some registry.

Taking a go at that here: https://github.com/willcl-ark/fork-observer/actions/runs/6024172731/job/16342330596

[0xB10C]

Some progress in #87