Add a RepositorySearchScore table and calculation to the RAC worker

This will be used in a followup PR to order search results instead of the RAC join. Currently, the join with the RAC table in search results in a lookup of ~600K rows, which causes searching to take ~6s. This PR denormalizes the data we need, as well as allowing us to score based on a wider band (6 months vs the current 1 week).

data/model/repository.py

@@ -12,7 +12,7 @@ from data.database import (Repository, Namespace, RepositoryTag, Star, Image, Im
                            Visibility, RepositoryPermission, RepositoryActionCount,
                            Role, RepositoryAuthorizedEmail, TagManifest, DerivedStorageForImage,
                            Label, TagManifestLabel, db_for_update, get_epoch_timestamp,
-                           db_random_func, db_concat_func)
+                           db_random_func, db_concat_func, RepositorySearchScore)
 from data.text import prefix_search
 from util.itertoolrecipes import take
 
@@ -42,6 +42,7 @@ def create_repository(namespace, name, creating_user, visibility='private', repo
 
   yesterday = datetime.now() - timedelta(days=1)
   RepositoryActionCount.create(repository=repo, count=0, date=yesterday)
+  RepositorySearchScore.create(repository=repo, score=0)
 
   if creating_user and not creating_user.organization:
     RepositoryPermission.create(user=creating_user, repository=repo, role=admin)