Broken links should only be shown in the list of broken links,
if current backend user has edit access to the field. This way
the editor will no longer get an error message on trying to
edit records he has no permission to edit.
Whether the editor has access depends on a number of factors.
We check the following:
The current permissions of the page. For editing the page, the editor must have
Permission::PAGE_EDIT, for editing content Permission::CONTENT_EDIT must be available.
The user has write access to the table. We check if the table
is in 'tables_modify' for the group(s).
The user has write access to the field. We check if the field
is an exclude field. If yes, it must be included in
'non_exclude_fields' for the group(s).
The user has write permission for the language of the record.
For tt_content: The CType is in list of explicitly allowed
values for authMode.