Set up Tests tab in circle CI

[josephjclark]

In #1294 we tried to set up the Tests tab in circle CI

And this is nice!

But the problem with that PR is that, although we have the nice UI summary, we lose information in the actual test output.

Here's an example of unit test output on that branch. There are 277 lines of output here - very little of it is valuable.

If I compare that to unit test output running on main, there are nearly 3000 lines of output, with details of each test and sometimes even additional test data that gets logged out.

Admittedly I don't use this detailed output very often, but I'm very nervous about losing access to it entirely.

[josephjclark]

Checkout branch fastlanes-xunit to see the fastlanes branch with the xunit stuff still in it.