feat: x/group tests to mocks (cosmos#12864)

## Description

Closes: cosmos#12763 



---

### 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...

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

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

scripts/mockgen.sh

@@ -19,5 +19,6 @@ $mockgen_cmd -source=x/auth/types/expected_keepers.go -package testutil -destina
 $mockgen_cmd -source=x/auth/ante/expected_keepers.go -package testutil -destination x/auth/ante/testutil/expected_keepers_mocks.go
 $mockgen_cmd -source=x/authz/expected_keepers.go -package testutil -destination x/authz/testutil/expected_keepers_mocks.go
 $mockgen_cmd -source=x/bank/types/expected_keepers.go -package testutil -destination x/bank/testutil/expected_keepers_mocks.go
+$mockgen_cmd -source=x/group/testutil/expected_keepers.go -package testutil -destination x/group/testutil/expected_keepers_mocks.go
 $mockgen_cmd -source=x/evidence/types/expected_keepers.go -package testutil -destination x/evidence/testutil/expected_keepers_mocks.go
 $mockgen_cmd -source=x/slashing/types/expected_keepers.go -package testutil -destination x/slashing/testutil/expected_keepers_mocks.go

store/v2alpha1/dbadapter/store_test.go

@@ -20,7 +20,7 @@ func TestAccessors(t *testing.T) {
 	mockCtrl := gomock.NewController(t)
 	defer mockCtrl.Finish()
 
-	mockDB := mocks.NewMockDBReadWriter(mockCtrl)
+	mockDB := mocks.NewMockReadWriter(mockCtrl)
 	store := dbadapter.Store{mockDB}
 	key := []byte("test")
 	value := []byte("testvalue")
@@ -64,7 +64,7 @@ func TestIterators(t *testing.T) {
 	mockCtrl := gomock.NewController(t)
 	defer mockCtrl.Finish()
 
-	mockDB := mocks.NewMockDBReadWriter(mockCtrl)
+	mockDB := mocks.NewMockReadWriter(mockCtrl)
 	store := dbadapter.Store{mockDB}
 	key := []byte("test")
 	value := []byte("testvalue")
@@ -91,7 +91,7 @@ func TestIterators(t *testing.T) {
 
 func TestCacheWraps(t *testing.T) {
 	mockCtrl := gomock.NewController(t)
-	mockDB := mocks.NewMockDBReadWriter(mockCtrl)
+	mockDB := mocks.NewMockReadWriter(mockCtrl)
 	store := dbadapter.Store{mockDB}
 
 	cacheWrapper := store.CacheWrap()