community-records: allow scan search

* Adds `scan` and `scan_params` arguments to
  `CommunityRecordsService.search(...)`, to allow for serving scan
  results (but only via the service).

invenio_rdm_records/services/community_records/service.py

@@ -45,6 +45,8 @@ def search(
         params=None,
         search_preference=None,
         extra_filter=None,
+        scan=False,
+        scan_params=None,
         **kwargs,
     ):
         """Search for records published in the given community."""
@@ -76,7 +78,12 @@ def search(
             permission_action="read",
             **kwargs,
         )
-        search_result = search.execute()
+
+        if scan:
+            scan_params = scan_params or {}
+            search_result = search.scan(**scan_params)
+        else:
+            search_result = search.execute()
 
         return self.result_list(
             self,