Track last read and write operation per repository

Problem to solve

We know how many users are performing AMAU activity with regards to repositories, but we don't know what proportion of repositories are being actively used. This would be useful to know so that we can better understand what kinds of projects are active, and how many projects are inactive.

Further details

Read-access is particularly interesting for modelling different feature proposals for offloading inactive repositories to cheaper storage. Read and write activity are both needed to understand access patterns, and model properly.

Proposal

It would be useful for the usage ping to have:

• count of all repositories (we might already have this)
• count of repositories with read events
• count of repositories with write events

If we know which repositories are active, it would be useful to join with repo size

• sum of sizes of all repositories
• sum of sizes of repositories with read events
• sum of sizes of repositories with write events