colossus data object id cache refactor

[mnaamani]

Some notes:

https://github.com/Joystream/joystream/pull/5026/files#diff-3b4764082ce211c8cca89a87bbbdf94a419f57bf37ba226617e223927cda1fefR8

[kdembler]

We currently keep a counter for "processes" accessing a given object so we don't delete anything that's being downloaded. The idea is that we can delegate this to the OS and get rid of custom logic in Colossus