* add function to convert StateTransition to LokiEntry
* add QueryResultBuilder
* update backtesting to produce result similar to historian
* make shouldRecord public
* filter out noop transitions
* add experimental front-end
* add new fields
* move conversion of api model to AlertRule to validation
* add extra labels
* calculate tick timestamp using the same logic as in scheduler
* implement correct logic of calculating first evaluation timestamp
* add uid, group and folder uid they are needed for jitter strategy
* add JitterOffsetInDuration and JitterStrategy.String()
* add config `backtesting_max_evaluations` to [unified_alerting] (not documented for now)
* remove obsolete tests
* elevate permisisons for backtesting endpoint
* move backtesting to separate dir
* add test for the bug
* update backtesting evaluators to accept a number of evaluations instead of `to` to have control over the number evaluations in one place
* 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`
Yuri Tseretyan
Ryan McKinley