Document activities used by rucio-daemons

[dynamic-entropy]

Will it be possible for an expert to Document the list of standard activities used by various daemons?
Though you get some hints from the name, it is not entirely clear why certain transfers are happening.

A few examples would be

• Data Consolidation
• Data Rebalancing
• Recovery

Originally posted by @dynamic-entropy in rucio/rucio#6738

[maxnoe]

Yes, please! A short description of the responsibilities of each daemon and what they are required for is missing from the docs.