.only support across all files

[Autre31415]

In a test suite with multiple files I attempted to use a .only to run a single test and noticed rather quickly that it only applied that exclusivity across that one test file, while every test in every other file ran.

According to the docs this is intended behavior, but I find this rather confusing given this was covered in #549 and subsequently solved in #556 over 3 years ago.

I did a little digging through the PR history and hadn't found any obvious indicators that the feature was reverted, so I'm wondering if it was done so intentionally and if so why?

Edit: I found #1467 and #1472. Closing this and upvoting that issue