rpc: simplify and consolidate response construction (#7725)

Responses are constructed from requests using MakeResponse, MakeError, and
MakeErrorf. This ensures the response is always paired with the correct ID,
makes cases where there is no ID more explicit at the usage site, and
consolidates the handling of error introspection across transports.

The logic for unpacking errors and assigning JSON-RPC response types was
previously duplicated in three places. Consolidate it in the types package for
the RPC subsystem.

* update test cases

internal/rpc/core/events.go

@@ -67,7 +67,7 @@ func (env *Environment) Subscribe(ctx context.Context, query string) (*coretypes
 				return
 			} else if errors.Is(err, tmpubsub.ErrTerminated) {
 				// The subscription was terminated by the publisher.
-				resp := rpctypes.RPCServerError(subscriptionID, err)
+				resp := callInfo.RPCRequest.MakeError(err)
 				ok := callInfo.WSConn.TryWriteRPCResponse(opctx, resp)
 				if !ok {
 					env.Logger.Info("Unable to write response (slow client)",
@@ -77,7 +77,7 @@ func (env *Environment) Subscribe(ctx context.Context, query string) (*coretypes
 			}
 
 			// We have a message to deliver to the client.
-			resp := rpctypes.NewRPCSuccessResponse(subscriptionID, &coretypes.ResultEvent{
+			resp := callInfo.RPCRequest.MakeResponse(&coretypes.ResultEvent{
 				Query:  query,
 				Data:   msg.Data(),
 				Events: msg.Events(),