Get more processing power on GH

Summary

GH actions "free" has several processing limits see

https://docs.github.com/en/enterprise-cloud@latest/actions/learn-github-actions/usage-limits-billing-and-administration

as we use more and more from GH this becomes a bottle-neck (especially for the "eclipse" organization that hosts a lot of projects), I therefore like to start the process of evaluate if/how we could get more processing power, this might include:

1. Choosing an 'Enterprise' Plan, maybe even a custom contract
2. Adding EF hosted runners see https://docs.github.com/en/enterprise-cloud@latest/actions/hosting-your-own-runners/about-self-hosted-runners#usage-limits
3. a combination of both

I think especially the opportunity for adding windows+mac runs is very useful as this was always problematic/limited on the Jenkins Infrastructure.

FYI @emerks @akurtakov @aloskutov @mistria ... and maybe more ...