when `name` of a Field overlaps an existing resolver throw an error

can be tested easily with 
```ts
  @ArrayField({
    name: 'aaa'
  })
  async getRelatedCampaigns(@Context ctx: UserSessionContext) {
  }

  @ArrayField({
    name: 'aaa'
  })
  async getRelatedDashboards(@Context ctx: UserSessionContext) {
}
}

```

currently we override without any warning/fail