Merge #2178

2178: Network tracers r=coot a=coot

This PR improves network tracers; originally done in `coot/p2p-integration` branch,
but this part is indepentend of p2p changes in `ouroboros-network`.  This PR consists of two patches:

- Improved mini-protocol tracers
  Which includes agency together with the mini-protocol message tag.

- networking trace using show instances rather than json values


Co-authored-by: Marcin Szamotulski <profunctor@pm.me>

cardano-node/src/Cardano/Tracing/Constraints.hs

@@ -5,6 +5,8 @@ module Cardano.Tracing.Constraints
   ( TraceConstraints
   ) where
 
+import           Prelude (Show)
+
 import           Data.Aeson
 
 import           Cardano.BM.Tracing (ToObject)
@@ -38,4 +40,6 @@ type TraceConstraints blk =
     , ToObject (ValidationErr (BlockProtocol blk))
     , ToObject (CannotForge blk)
     , ToObject (ForgeStateUpdateError blk)
+    , Show blk
+    , Show (Header blk)
     )