Service rate limits

[lbarcziova]

• Implement user/namespace/project usage metrics #1990
• Based on the measured data set the user/namespace/project limits #2052

[lachmanfrantisek]

After a team discussion, we didn't pick this as a top Packit team priority for the next quarter and preferred epics with bigger user benefits. (Sadly, we have limited resources...) If anyone wants to help us with this, we will be really glad. We are open to any collaboration and have already successfully implemented/started multiple affords thanks to people outside of the Packit team.