frame-title rule should account for presentational conflict

[WilcoFiers]

The following should fail the frame-title rule:

<iframe title=" " src="/test-assets/SC4-1-2-frame-doc.html" role="none"> </iframe>

https://wai-wcag-act-rules.netlify.app/standards-guidelines/act/rules/cae760/proposed/#failed-example-4

[straker]

To resolve this, we need to update the isNativelyFocusable code to say that iframe and frame elements are natively focusable. That will then trigger the conflict resolution code in the getRole function.

[padmavemulapati]

Validated with the latest axe-core develop branch code base, the test script: <iframe title=" " src="/test-assets/SC4-1-2-frame-doc.html" role="none"> </iframe> is failing for frame-title rule