Added interface to accept any type of ADR 031 message router. (#2058)

## Description

Updated the controller and host keeper to take in an interface for the router. This allows systems that implement ADR 031, but do not use the default baseapp.router to use ICA.

closes: #2044 

---

Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
write a little note why.

- [ ] Targeted PR against correct branch (see [CONTRIBUTING.md](https://github.com/cosmos/ibc-go/blob/master/CONTRIBUTING.md#pr-targeting))
- [ ] Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
- [ ] Code follows the [module structure standards](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules/structure.md).
- [ ] Wrote unit and integration [tests](https://github.com/cosmos/ibc-go/blob/master/CONTRIBUTING.md#testing)
- [ ] Updated relevant documentation (`docs/`) or specification (`x/<module>/spec/`)
- [ ] Added relevant `godoc` [comments](https://blog.golang.org/godoc-documenting-go-code).
- [ ] Added a relevant changelog entry to the `Unreleased` section in `CHANGELOG.md`
- [ ] Re-reviewed `Files changed` in the Github PR explorer
- [ ] Review `Codecov Report` in the comment section below once CI passes

CHANGELOG.md

@@ -64,6 +64,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (transfer) [\#2034](https://github.com/cosmos/ibc-go/pull/2034) Transfer Keeper now expects a keeper which fulfills the expected `ScopedKeeper` interface for the capability keeper.
 * (05-port) [\#2025](https://github.com/cosmos/ibc-go/pull/2025) Port Keeper now expects a keeper which fulfills the expected `ScopedKeeper` interface for the capability keeper.
 * (04-channel) [\#2024](https://github.com/cosmos/ibc-go/pull/2024) Channel Keeper now expects a keeper which fulfills the expected `ScopedKeeper` interface for the capability keeper.
+* (apps/27-interchain-accounts) [\#2058](https://github.com/cosmos/ibc-go/pull/2058) Added `MessageRouter` interface and replaced `*baseapp.MsgServiceRouter` with it. The controller and host keepers of apps/27-interchain-accounts have been updated to use it.
 
 ### State Machine Breaking
 

modules/apps/27-interchain-accounts/controller/keeper/keeper.go

@@ -4,7 +4,6 @@ import (
 	"fmt"
 	"strings"
 
-	baseapp "github.com/cosmos/cosmos-sdk/baseapp"
 	"github.com/cosmos/cosmos-sdk/codec"
 	storetypes "github.com/cosmos/cosmos-sdk/store/types"
 	sdk "github.com/cosmos/cosmos-sdk/types"
@@ -30,14 +29,14 @@ type Keeper struct {
 
 	scopedKeeper icatypes.ScopedKeeper
 
-	msgRouter *baseapp.MsgServiceRouter
+	msgRouter icatypes.MessageRouter
 }
 
 // NewKeeper creates a new interchain accounts controller Keeper instance
 func NewKeeper(
 	cdc codec.BinaryCodec, key storetypes.StoreKey, paramSpace paramtypes.Subspace,
 	ics4Wrapper icatypes.ICS4Wrapper, channelKeeper icatypes.ChannelKeeper, portKeeper icatypes.PortKeeper,
-	scopedKeeper icatypes.ScopedKeeper, msgRouter *baseapp.MsgServiceRouter,
+	scopedKeeper icatypes.ScopedKeeper, msgRouter icatypes.MessageRouter,
 ) Keeper {
 	// set KeyTable if it has not already been set
 	if !paramSpace.HasKeyTable() {

modules/apps/27-interchain-accounts/host/keeper/keeper.go

@@ -4,7 +4,6 @@ import (
 	"fmt"
 	"strings"
 
-	baseapp "github.com/cosmos/cosmos-sdk/baseapp"
 	"github.com/cosmos/cosmos-sdk/codec"
 	storetypes "github.com/cosmos/cosmos-sdk/store/types"
 	sdk "github.com/cosmos/cosmos-sdk/types"
@@ -30,14 +29,14 @@ type Keeper struct {
 
 	scopedKeeper icatypes.ScopedKeeper
 
-	msgRouter *baseapp.MsgServiceRouter
+	msgRouter icatypes.MessageRouter
 }
 
 // NewKeeper creates a new interchain accounts host Keeper instance
 func NewKeeper(
 	cdc codec.BinaryCodec, key storetypes.StoreKey, paramSpace paramtypes.Subspace,
 	channelKeeper icatypes.ChannelKeeper, portKeeper icatypes.PortKeeper,
-	accountKeeper icatypes.AccountKeeper, scopedKeeper icatypes.ScopedKeeper, msgRouter *baseapp.MsgServiceRouter,
+	accountKeeper icatypes.AccountKeeper, scopedKeeper icatypes.ScopedKeeper, msgRouter icatypes.MessageRouter,
 ) Keeper {
 	// ensure ibc interchain accounts module account is set
 	if addr := accountKeeper.GetModuleAddress(icatypes.ModuleName); addr == nil {

modules/apps/27-interchain-accounts/types/router.go

@@ -0,0 +1,12 @@
+package types
+
+import (
+	baseapp "github.com/cosmos/cosmos-sdk/baseapp"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+)
+
+// MessageRouter ADR 031 request type routing
+// https://github.com/cosmos/cosmos-sdk/blob/main/docs/architecture/adr-031-msg-service.md
+type MessageRouter interface {
+	Handler(msg sdk.Msg) baseapp.MsgServiceHandler
+}