feat!: remove legacy REST (#9594)

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## Description

ref: #7517 

  * [x] Remove the x/{module}/client/rest folder
  * [x] Remove all glue code between simapp/modules and the REST server

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---

### Author Checklist

*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*

I have...

- [x] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [x] added `!` to the type prefix if API or client breaking change
- [x] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#pr-targeting))
- [x] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#testing)
- [x] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification - see #9615
- [x] reviewed "Files changed" and left comments if necessary
- [x] confirmed all CI checks have passed

### Reviewers Checklist

*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [x] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [x] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [x] reviewed API design and naming
- [ ] reviewed documentation is accurate - see #9615
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

types/module/module_test.go

@@ -6,9 +6,9 @@ import (
 	"testing"
 
 	"github.com/cosmos/cosmos-sdk/codec/types"
+	"github.com/gorilla/mux"
 
 	"github.com/golang/mock/gomock"
-	"github.com/gorilla/mux"
 	"github.com/spf13/cobra"
 	"github.com/stretchr/testify/require"
 	abci "github.com/tendermint/tendermint/abci/types"
@@ -38,9 +38,9 @@ func TestBasicManager(t *testing.T) {
 	mockAppModuleBasic1.EXPECT().Name().AnyTimes().Return("mockAppModuleBasic1")
 	mockAppModuleBasic1.EXPECT().DefaultGenesis(gomock.Eq(cdc)).Times(1).Return(json.RawMessage(``))
 	mockAppModuleBasic1.EXPECT().ValidateGenesis(gomock.Eq(cdc), gomock.Eq(nil), gomock.Eq(wantDefaultGenesis["mockAppModuleBasic1"])).Times(1).Return(errFoo)
-	mockAppModuleBasic1.EXPECT().RegisterRESTRoutes(gomock.Eq(client.Context{}), gomock.Eq(&mux.Router{})).Times(1)
 	mockAppModuleBasic1.EXPECT().RegisterLegacyAminoCodec(gomock.Eq(legacyAmino)).Times(1)
 	mockAppModuleBasic1.EXPECT().RegisterInterfaces(gomock.Eq(interfaceRegistry)).Times(1)
+	mockAppModuleBasic1.EXPECT().RegisterRESTRoutes(gomock.Eq(client.Context{}), gomock.Eq(&mux.Router{})).Times(1)
 	mockAppModuleBasic1.EXPECT().GetTxCmd().Times(1).Return(nil)
 	mockAppModuleBasic1.EXPECT().GetQueryCmd().Times(1).Return(nil)