Some Item edit pages are accessible by anonymous users

[ybnd]

Describe the bug
A few of the item/*/edit/* pages do not seem to have properly configured guards.
As far as I see all of these pages are non-functional, so the impact of this bug is minimal.

It's likely that there are other similar cases -- would be good to look for more examples and address them in one go.

To Reproduce
Steps to reproduce the behavior:

1. Go to any of the following pages without logging in to DSpace:
   • https://demo.dspace.org/items/70076a29-850a-4af5-b382-2cce72ed5205/edit/access-control
   • https://demo.dspace.org/items/70076a29-850a-4af5-b382-2cce72ed5205/edit/curate
2. The actual page will render, but will not be usable (e.g. due to missing data, failing REST requests)

Expected behavior
Users without the necessary authorizations (and especially anonymous users) should not have access to administrator pages.
Instead, they should be redirected to the login page, or be shown a 403 page.

Related work
#2247

[tdonohue]

@ybnd : If you (or your team) happen to have any time in the next few days, it would be good to patch these quickly for 7.6.1 (which I hope we get out next week sometime). I agree the pages don't seem to be usable at all, but it'd be good to fix them nonetheless.