presentation-role-conflict should also fail on img with empty alt and aria-label

Axe-core should fail the following in the `presentation-role-conflict` rule:

```html
<img alt="" aria-label="Hello world" />
```

This image gets ignored in voiceover + Safari. This issue came up as part of ACT: https://wai-wcag-act-rules.netlify.app/standards-guidelines/act/implementations/axe-core/#breakdown-46ca7f