Action ignored, query detected "invalid input syntax for type uuid"

### Version Information

Server Version: v2.7.0

### Environment

OSS

### What is the expected behaviour?

Hasura Action should validate the types declared in its input type.

### Keywords

action, type, uuid, invalid input syntax

### What is the current behaviour?

Hasura Action does not validate the types declared in its input type.

### How to reproduce the issue?

1. Create an action:

```
type Mutation {
custom_insert_user_one(
object: custom_user_insert_input!
): custom_user
}

input custom_user_insert_input {
id: uuid!
name: String
}

type custom_user {
id: uuid!
name: String
}
```

2. Action handler should query some table:

```
query($id: uuid!) {
some_table(where: {some_id: {_eq: $id}}) {
id
}
}
```

3. Pass the broken UUID value to the action:

```
mutation($id: uuid!) {
custom_insert_user_one(object: {id: $id, name: "test"}) {name}
}

{"id": "123456789-1234-1234-1234-123456789012"}
```

4. Observe an unexpected error:

```
{
"errors": [
{
"extensions": {
"path": "$",
"code": "unexpected"
},
"message": "not a valid json response from webhook"
}
]
}
```

5. Check the logs of the action handler
6. Find the validation error detected by the `query` above:

```
{
"errors": [
{
"extensions": {
"path": "$",
"code": "data-exception"
},
"message": "invalid input syntax for type uuid: \"123456789-1234-1234-1234-123456789012\""
}
]
}
```

Action handler expects the value to be already validated by Hasura Action,
but Hasura Action does not even try to validate this value,
despite being required to do so with `id: uuid!` in the input type.

### Any possible solutions?

Please validate the values passed to actions in the same way you validate them in table queries/mutations.

### If the bug is confirmed, would you be willing to submit a PR?

No