Implement bulk actions

We need bulk actions when a lot of items are involved like approving an ingest. There are - as I see it - three ways how to handle this (and in principle, all of this three ways could operate in parallel):

• Define an API endpoint where a bulk operation could be started, e.g. approve all items with status ingested from source x (disadvantage: take it or leave it - granularity could be a problem)
• Have in frontend a list with checkboxes to select all the items that are involved + a button where every checkbox could be activated in bulk: after (de)selecting run the bulk action (disdavantage: pagination is a problem as you can only check the items from one page)
• Use the Python notebooks to run such an operation (disadvantage: maybe necessary to write custom Python code, no full integration in the frontend)

Open for discussion to find a solution: @matej.durco @lbarbot @mkozak @edward.gray @frank.fischer01 @stefan.probst @cesare.concordia