Add "number of tests passed" endpoint

[heythisischris]

Overview

Per Gen Herres request:

hello again, for reporting info to clients, one of the biggest asks is always “what is the number of tests passed / percentage of tests passed”. I don’t see anything obvious to me to help get that info. Is there anything anywhere?

I propose adding a simple endpoint, GET /stats which takes either a reportId, propertyId, or urlId param. It then returns the requested stats:

{
	"equalified": 12,
	"active": 24,
	"total": 36,
	"tests_passed": 5,
	"tests_passed_percentage": 0.2
}

Requested bounty

I predict this will take 1 hour to develop/deploy.

[bbertucc]

Approved.

[bbertucc]

Just adding a note that this falls into the "issue density" feature discussed in #373.