Improve UX of QA review embedded replay page navigation

[SuaYoo]

Context

We've currently disabled navigation within the QA review replay frame since there's no way of indicating to users whether the link has been crawled, or allowing them to exit 404 pages. A better user experience would be to allow users to navigate in the replay in sync with the QA review page list.

Requirements

• Notify <replay-web-page> consumers when navigation occurs
• Browsertrix API consumers should be able to check whether a page URL is a part of a QA run

Implementation details

• Fire event from <replay-web-page> when navigation is finished.
• Navigation event should contain error details like 404 status.
• Could be either new API endpoint or a url filter on the existing GET /pages endpoint.

Questions

Can we also fire an event when navigation begins? Maybe reuse logic for showing the loading spinner?

[SuaYoo]

Might be achievable with an API GET endpoint that filters pages by page URL

[tw4l]

@ikreymer Define what's needed in backend and split into additional issues

[Shrinks99]

From today's call: Goal is to get this done before QA is considered out of "beta"