Move database classes and functions from kojihub.py to koji/db.py

Move QueryProcessor, InsertProcessor, UpdateProcessor,
BulkInsertProcessor, _applyQueryOpts, get_event, _dml,
_fetchMulti, _fetchSingle, _singleValue, _multiRow, _singleRow

Update koji-sweep-db script to DB Processors

Fixes: https://pagure.io/koji/issue/3466

plugins/hub/protonmsg.py

@@ -17,7 +17,8 @@ from proton.reactor import Container
 import koji
 from koji.context import context
 from koji.plugin import callback, convert_datetime, ignore_error
-from kojihub import QueryProcessor, InsertProcessor, get_build_type
+from kojihub import get_build_type
+from koji.db import QueryProcessor, InsertProcessor
 
 CONFIG_FILE = '/etc/koji-hub/plugins/protonmsg.conf'
 CONFIG = None