Add count of projects with CODEOWNERS file to usage ping
Problem to solve
We don't have any usage metrics for CODEOWNERS!
Proposal
Add the following counts to the usage ping:
- count of merge requests with required code owners
- count of merge requests with optional code owners
- count of projects with code owners
When combined with the count of merge requests, we'll be able to understand how often they are used proportional to total number of MRs in the instance, and the number of projects they are used in relative to total projects on the instance.