Feature request: consolidate stats from multiple repositories into a single report

[jt-nti]

It's great to be able to collect data from multiple repositories using the jobs.<job_id>.strategy.matrix directive however it would also be really useful to easily compare related repositories with a single consolidated report.

In the mean time I've had a go at hacking together a script to collect together data from the ghrs-data directories, which seems to be working so far 🤞

https://github.com/cicsdev/repo-stats/blob/main/scripts/cicsdev-summary.sh