[ENG-10309] Add meta to API preprint detail view to indicate spam status (CenterForOpenScience#11604)

* indicate if the preprint is spammy with meta: {flagged_content: true}

* make sure that the sitemap doesn’t include any spammy preprint.

* update generate sitemap test

* get base get_meta in child meta to keep all needed meta data

* exclude spam content for preprints sitemap

* unify server response on getting specific registry/node/preprint if it is spammy to make it possible to create info page on front end

* exclude spam from Nodes and Registrations on sitemap generation

* avoid errors for objects where spam may not be determined

* update code

* show more specific message for spammy resource on contributor access {'flagged_content': True} to render specific UI to show contributor how to get support to ham the resource

* implement unittests for spammy resource contributor access

* refactor code

* show if resource is spammed on retrieval to all types of user

* add tests

* ensure that the sitemap is working correctly for spammed content

* Delete api_tests/preprints/views/test_preprint_detail_new_behaviors.py

remove not needed test

* raise Gone for deleted not spammed preprint to keep it same as for other deleted resources

* change 404 to 410 for deleted preprints in tests

* change 404 to 410 for deleted preprints in tests

Author: mkovalua

api/preprints/views.py

@@ -139,7 +139,6 @@ def get_preprint(self, check_object_permissions=True, ignore_404=False):
                 sentry.log_message(f'Preprint deleted: [guid={base_guid_id}, version={preprint_version}]')
                 raise Gone(detail='The requested preprint is no longer available.')
 
-        user = self.request.user
         if isinstance(user, AnonymousUser):
             user_is_reviewer = user_is_contributor = False
         else: