Pass result to query.post() hooks

### Prerequisites

- [x] I have written a descriptive issue title
- [x] I have searched existing issues to ensure the feature has not already been requested

### 🚀 Feature Proposal

Re: https://github.com/Automattic/mongoose/pull/15898, `query.post()` hooks should receive the query result as a parameter:

```javascript
query.post(function(result) {
if (result.deletedCount > 0) {
// Handle successful delete
}
});
```

### Motivation

_No response_

### Example

_No response_

Start by tracing the query.post() hook handling and review the behavior discussed in pull request #15898. The change is complete when post hooks receive the query result, including result.deletedCount for delete operations, with coverage for the new callback argument.

Written by the indexing model from the issue text.