data diffusion startup in cardano-node

Currently the flow of data in `cardano-node` is not very clear. Partially the
confusion comes from the fact that `runDataDiffusion` is run by consensus
application. The current flow is:

_environment_ (genesis, config, cli options)
→ _consensus protocol setup_
→ _consensus options & network options_
→ _consensus_ starts data diffusion

Some network options go into consensus like network magic (it's needed to start
protocols), some not (node addresses for diffusion). We should have something
like this:
```
runDataDiffusion
∷ DiffusionArguments
→ (NetworkArgumentsRequiredByConsensus → m NodeToNodeProtocols)
→ m Void
```

`NetworkArgumentsRequiredByConsensus` would be passed as part of
`DiffusionArguments` and they can come from _environment_ (genesis, CLI args,
etc), without going through consensus setup first (the `protocolInfo` and
friends).