Write tests for HTML-AAM host-language-reserved roles

[cookiecrook]

Core-AAM includes the following comments on host language specific computed roles. (Cite: after Example 2)

When host language elements do not have an exact or equivalent mapping to a valid, non-abstract role, the related Accessibilty API Mapping extension specification MAY specify a unique computedrole string as the return value for interoperability testing purposes, such as

<video> <!-- computedrole returns "html-video" -->

<main role="html-video"> <!-- Author error. computedrole returns "main" -->

HTML-AAM is the first AAM spec to define some of these. html-input-file is an example.
https://www.w3.org/TR/html-aam-1.0/#el-input-file

We should add some WPT tests in order to:

• verify these new computed roles are returned for host language elements.
• verify that it's a no-op if authors add them: (<div role="html-input-file"> is an author error and MUST NOT result changing the computedrole)

Note: these engine changes will be reflected in browser accessibility developer features as well... For example, once the change is made in WebKit's WebCore Accessibility, the role change will be visible in the WebKit Web Inspector DOM Accessibility pane. I assume the same is true of other browser's web dev tools.

[cookiecrook]

Downstream from ARIA 1887 (2023 work to get WPT Accessibility project spun up)

• Need a decision on what the computedrole should return on extension specs w3c/aria#1887