limit xls-collection-crosswalk to group members

[floriangantner]

Is your feature request related to a problem? Please describe.
By default there is some crosswalk collection-xls to xls using the collection default submission form.
This is used for exporting the items via collection-export process. By default it is also shown for anonymous users in the export format list.
Most anonymous users are not sure how the structure is (what is the $$sl=? What are the separators? What is some placeholder?) and do not need these information; some more abstract export for anonymous users in xls is available using the CsvCrosswalk/XlsCrosswalk

Describe the solution you'd like
Implement the isAuthenticated method from the interface ItemExportCrosswalk as the others crosswalk do. This allow system administrators to limit it to Administrators and/or Anonymous users

Describe alternatives or workarounds you've considered

• remove it from the crosswalks list. The bean should be initialized anyway and export is possible anyway

Additional context
https://github.com/4Science/DSpace/blob/main-cris/dspace-api/src/main/java/org/dspace/content/integration/crosswalks/XlsCollectionCrosswalk.java