Reduce bitstream authorization requests

[tinsch]

Description

This PR reduces the number of calls made to the REST API by executing certain authorization requests only conditionally when the normal download is not possible to the user. This improves the performance for items with a large number of bitstreams and a large pagesize (>=50), as can be seen in a graph below.

⚠️Note: this PR currently fails tests and is therefore marked as a Draft PR

Instructions for Reviewers

Currently the response time is slow for items with a large number of bitstreams. The current workaround are small pageSizes for the item's bitstreams. However, from a UX standpoint it would be nice to be able to show a larger list of bitstreams to the users, especially in the case of uploaded research data.

How to test this PR:

• create an Item with >=50 bitstreams
• edit some bitstreams, so that they are embargoed, or the access is otherwise restricted to anonymous users
• set item.bitstream.pageSize to 50 (or more)
• check that the response time is slower without this PR on the item page, and faster with the PR changes
• check that the "Request a copy" functionality still works for embargoed and otherwise restricted items

Here is a comparison of the reponse time of an item page, varied in the page size:

Checklist

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