Broker2Broker: Introduce Main Broker

[s1341]

When using Broker2Broker, there should be a Main Broker to which all other brokers connect.

This Main Broker should:

• display stats for the entire cluster, including total number of clients, executions, exec/secs, and objectives.
• for OnDiskCorpus, it should collect all the TestCases and objective outputs from all connected brokers.

This will make managing a multi-machine fuzzing campaign much easier.

Ideally, it should be possible to run a Main Broker without any clients of its own. It should also be possible to run Main Broker on a PC, while child-brokers and clients run on e.g. phones.

[andreafioraldi]

for OnDiskCorpus, it should collect all the TestCases and objective outputs from all connected brokers.

That's not possible because maybe there are clients with different configurations (so different metadata) and maybe even different objectives. We can however report the stats.

Ideally, it should be possible to run a Main Broker without any clients of its own. It should also be possible to run Main Broker on a PC, while child-brokers and clients run on e.g. phones.

Yes agree

[domenukk]

Sending over the Input should definitely be doable and should be done, though, IMHO? Even sending over metadata makes sense (and disregarding it if it doesn't match the current config)