Make client.Context implement gRPC ClientConn (#6342)

* Add QueryConn to client.Context

* Add integration test

* imports

* spelling

* Make client.Context implement grpc ClientConn

Co-authored-by: Alexander Bezobchuk <alexanderbez@users.noreply.github.com>
Co-authored-by: Federico Kunze <31522760+fedekunze@users.noreply.github.com>

simapp/app.go

@@ -4,8 +4,6 @@ import (
 	"io"
 	"os"
 
-	"github.com/cosmos/cosmos-sdk/codec/types"
-
 	abci "github.com/tendermint/tendermint/abci/types"
 	"github.com/tendermint/tendermint/libs/log"
 	tmos "github.com/tendermint/tendermint/libs/os"
@@ -13,6 +11,8 @@ import (
 
 	"github.com/cosmos/cosmos-sdk/baseapp"
 	"github.com/cosmos/cosmos-sdk/codec"
+	"github.com/cosmos/cosmos-sdk/codec/testdata"
+	"github.com/cosmos/cosmos-sdk/codec/types"
 	"github.com/cosmos/cosmos-sdk/std"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/types/module"
@@ -306,6 +306,9 @@ func NewSimApp(
 	app.mm.RegisterRoutes(app.Router(), app.QueryRouter())
 	app.mm.RegisterQueryServices(app.GRPCQueryRouter())
 
+	// add test gRPC service for testing gRPC queries in isolation
+	testdata.RegisterTestServiceServer(app.GRPCQueryRouter(), testdata.TestServiceImpl{})
+
 	// create the simulation manager and define the order of the modules for deterministic simulations
 	//
 	// NOTE: this is not required apps that don't use the simulator for fuzz testing