Add `reindex-priority` parameter to PUT and POST calls

[shirey]

Add a new optional query parameter to all update/PUT and create/POST endpoints to pass the priority of reindexing to the search-api reindex process. The new parameter, reindex-priority has three allowable values- 1, 2 or 3. Pass this priority to the search-api /reindex endpoint. This parameter is optional and if not provided, the existing search-api reindex functionality will default to priority 1. The will need to be a mutually exclusive (only one can exist) parameter with the existing reindex=false flag.