Feature request: Add lateral navigation in HTML report

[kevemueller]

When producing the HTML report, kyua creates isolated pages that are only referenced from the index page.
If you have a lot of failed tests, e.g. after introducing a sanitizer to a legacy code base, you would like to skim through the failures to detect recurring patterns.
This could be made very efficient if the test page summary had "previous failure" / "up to index" / "next failure" navigation links.