Move generic JSON RPC logic into its own files.

mar/json/rpc/response.hoon

@@ -1,7 +1,7 @@
 ::
-/-  ethereum
+/-  json-rpc
 /+  httr-to-json
-=,  json-rpc:ethereum
+=,  json-rpc
 ::
 |_  res=response
 ::

sur/ethereum.hoon

@@ -39,25 +39,4 @@
         [%label l=?(%earliest %latest %pending)]
     ==
   --
-::
-::  json-rpc
-::
-++  json-rpc
-  |%
-  ++  response
-    $%  [%result res=@t]
-        [%error code=@t message=@t]  ::TODO  data?
-    ==
-  ::
-  ++  request
-    $:  method=@t
-        params=parameters
-        id=(unit @t)  ::TODO  ?
-    ==
-  ::
-  ++  parameters
-    $%  [%array (list @t)]
-        [%object (map @t @t)]
-    ==
-  --
 --

sur/json/rpc.hoon

@@ -0,0 +1,6 @@
+|%
+++  response  ::TODO  id and jsonrpc fields?
+  $%  [%result res=@t]
+      [%error code=@t message=@t]  ::TODO  data?
+  ==
+--