fix: authz with denylist (#11403)

## Description

Closes: #11391 



---

### 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/master/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/master/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/master/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)

x/staking/types/authz.go

@@ -94,7 +94,7 @@ func (a StakeAuthorization) Accept(ctx sdk.Context, msg sdk.Msg) (authz.AcceptRe
 		}
 	}
 
-	if !isValidatorExists {
+	if len(allowedList) > 0 && !isValidatorExists {
 		return authz.AcceptResponse{}, sdkerrors.ErrUnauthorized.Wrapf("cannot delegate/undelegate to %s validator", validatorAddress)
 	}
 

x/staking/types/authz_test.go

@@ -120,7 +120,20 @@ func TestAuthzAuthorizations(t *testing.T) {
 			false,
 			nil,
 		},
-
+		{
+			"delegate: testing with a validator out of denylist",
+			[]sdk.ValAddress{},
+			[]sdk.ValAddress{val1},
+			stakingtypes.AuthorizationType_AUTHORIZATION_TYPE_DELEGATE,
+			nil,
+			stakingtypes.NewMsgDelegate(delAddr, val2, coin100),
+			false,
+			false,
+			&stakingtypes.StakeAuthorization{
+				Validators: &stakingtypes.StakeAuthorization_DenyList{
+					DenyList: &stakingtypes.StakeAuthorization_Validators{Address: []string{val1.String()}},
+				}, MaxTokens: nil, AuthorizationType: stakingtypes.AuthorizationType_AUTHORIZATION_TYPE_DELEGATE},
+		},
 		{
 			"undelegate: expect 0 remaining coins",
 			[]sdk.ValAddress{val1, val2},