* do not suppress NoData state
* extract conversion of state to postable alert + tests
* create a special alert instance if nodata
* use NoData when converting from Keep Last State instead of Alerting
* add silence during migration if NoData is mapped to KeepLastState.
* move evaluation function out of loop
* extract updateRule function
* isolate alertRule change. update returns new rule and the evaluation accepts the rule as argument
* extract retry loop into a function
* add function wide log context.
* refactor metrics + add tests + replace timeNow with schedule.clock
* keep existing unified alert rules untouched
* move silences and other alertmanager files to the organization directory (only if it is a single organization deployment)
* assign the existing notification settings and routes to the first organization
* create default notification settings for each organization in the case of multi org deployment
* Add method GetAllLatestAlertmanagerConfiguration to DBStore
* add method ApplyConfig to AlertManager
* update multiorg alert manager to load all alertmanager configs at once
Yuriy Tseretyan