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>

tests/cli/grpc_query_test.go

@@ -0,0 +1,28 @@
+// +build cli_test
+
+package cli
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/cosmos/cosmos-sdk/client"
+	"github.com/cosmos/cosmos-sdk/codec/testdata"
+)
+
+func TestCliQueryConn(t *testing.T) {
+	t.Parallel()
+	f := NewFixtures(t)
+
+	// start simd server
+	proc := f.SDStart()
+	t.Cleanup(func() { proc.Stop(false) })
+
+	ctx := client.NewContext()
+	testClient := testdata.NewTestServiceClient(ctx)
+	res, err := testClient.Echo(context.Background(), &testdata.EchoRequest{Message: "hello"})
+	require.NoError(t, err)
+	require.Equal(t, "hello", res.Message)
+}