Add GetTx gRPC endpoint (#7688)

* Add empty TxByHash

* Fix search & replace

* Renname to GetTx

* Make getTx grpc work

* Hash as string

* Add todo comment

* /tx

* Make tests pass

* Put into function

* Add changelog

* Fix lint

* RegisterTxService in server

* Remove comment

* Update proto/cosmos/tx/v1beta1/service.proto

Co-authored-by: Cory <cjlevinson@gmail.com>

* Create new protoCdc

* Move tx service to x/auth

* Small tweaks

* Link gh issue

* Fix lint

* Update x/auth/tx/service.go

Co-authored-by: Aleksandr Bezobchuk <alexanderbez@users.noreply.github.com>

Co-authored-by: Cory <cjlevinson@gmail.com>
Co-authored-by: Federico Kunze <31522760+fedekunze@users.noreply.github.com>
Co-authored-by: Aleksandr Bezobchuk <alexanderbez@users.noreply.github.com>
Co-authored-by: SaReN <sahithnarahari@gmail.com>

server/start.go

@@ -231,6 +231,9 @@ func startInProcess(ctx *Context, clientCtx client.Context, appCreator types.App
 		return err
 	}
 
+	// Add the tx service to the gRPC router.
+	app.RegisterTxService(clientCtx)
+
 	var apiSrv *api.Server
 
 	config := config.GetConfig(ctx.Viper)

server/types/app.go

@@ -10,6 +10,7 @@ import (
 	tmtypes "github.com/tendermint/tendermint/types"
 	dbm "github.com/tendermint/tm-db"
 
+	"github.com/cosmos/cosmos-sdk/client"
 	"github.com/cosmos/cosmos-sdk/server/api"
 	"github.com/cosmos/cosmos-sdk/server/config"
 )
@@ -37,6 +38,10 @@ type (
 		// RegisterGRPCServer registers gRPC services directly with the gRPC
 		// server.
 		RegisterGRPCServer(grpc.Server)
+
+		// RegisterTxService registers the gRPC Query service for tx (such as tx
+		// simulation, fetching txs by hash...).
+		RegisterTxService(clientCtx client.Context)
 	}
 
 	// AppCreator is a function that allows us to lazily initialize an