cardano-diffusion package

Introduced `cardano-diffusion` package.

Some things are hidden inside of it because that's how we are testing
things now, in particular `PeerSelection` and `Testnet` tests depend on
`Cardano` constructs.  In the future we could split them into general
test & cardano specific tests, this will be in particularly useful for
another non-trivial extension of `ouroboros-network`, but also might
organise tests better.

Author: coot

dmq-node/src/DMQ/Diffusion/Arguments.hs

@@ -50,7 +50,8 @@ diffusionArguments
   => Tracer m (NtN.HandshakeTr ntnAddr)
   -> Tracer m (NtC.HandshakeTr ntcAddr)
   -> Diffusion.Arguments
-       NoExtraState NoExtraDebugState NoExtraFlags NoExtraPeers NoExtraAPI NoExtraChurnArgs NoExtraCounters
+       NoExtraState NoExtraDebugState NoExtraFlags NoExtraPeers
+       NoExtraAPI NoExtraChurnArgs NoExtraCounters NoExtraTracer
        IOException
        Resolver
        m

dmq-node/src/DMQ/Tracer.hs

@@ -19,6 +19,7 @@ module DMQ.Tracer
   , NoExtraConfig (..)
   , NoExtraAPI (..)
   , NoExtraChurnArgs (..)
+  , NoExtraTracer (..)
   ) where
 
 import Codec.CBOR.Term (Term)
@@ -103,6 +104,10 @@ instance ToJSON NoExtraDebugState where
   omitField _ = True
 data NoExtraChurnArgs  = NoExtraChurnArgs
 data NoExtraAPI        = NoExtraAPI
+data NoExtraTracer     = NoExtraTracer
+instance ToJSON NoExtraTracer where
+  toJSON _ = Null
+  omitField _ = True
 
 instance ToJSON (Governor.PeerSelectionCounters NoExtraCounters) where
   toJSON Governor.PeerSelectionCounters {..} =
@@ -164,6 +169,7 @@ dmqDiffusionTracers
                        NoExtraFlags
                        NoExtraPeers
                        NoExtraCounters
+                       NoExtraTracer
                        m
 dmqDiffusionTracers
     Configuration {