* Use suggested value for uid
* update the snapshot
* use __expr__
* replace all -100 with __expr__
* update snapshot
* more changes
* revert redundant change
* Use expr.DatasourceUID where it's possible
* generate files
* Implement backtesting engine that can process regular rule specification (with queries to datasource) as well as special kind of rules that have data frame instead of query.
* declare a new API endpoint and model
* add feature toggle `alertingBacktesting`