* CloudWatch: Remove core imports from CloudWatchRequest and use appEvents for notifications
* add error message to variable query editor multi filters
* fix tests
* fix lint
* fix lint
* add test for non multi-variable
* pr comments
Fix unexpected error when creating a new cloudwatch datasource.
Involves a fair amount of refactoring, so if this causes unexpected issues related to region fetching we can turn this off with the cloudwatchNewRegionsHandler feature toggle, although we do not predict it will so we are enabling it to default to true and hope to remove it shortly.