Merge branch 'ds/maintenance-part-1'

A "git gc"'s big brother has been introduced to take care of more repository maintenance tasks, not limited to the object database cleaning. * ds/maintenance-part-1: maintenance: add trace2 regions for task execution maintenance: add auto condition for commit-graph task maintenance: use pointers to check --auto maintenance: create maintenance.<task>.enabled config maintenance: take a lock on the objects directory maintenance: add --task option maintenance: add commit-graph task maintenance: initialize task array maintenance: replace run_auto_gc() maintenance: add --quiet option maintenance: create basic maintenance runner