Migrations:
* add a new column alert_group_idx to alert_rule table
* add a new column alert_group_idx to alert_rule_version table
* re-index existing rules during migration
API:
* set group index on update. Use the natural order of items in the array as group index
* sort rules in the group on GET
* update the version of all rules of all affected groups. This will make optimistic lock work in the case of multiple concurrent request touching the same groups.
UI:
* update UI to keep the order of alerts in a group
* create AlertGroupKey structure
* update PrometheusSrv.
- extract creation of RuleGroup to a separate method. Use group key for grouping
* update RuleSrv
- update calculateChanges to use groupKey
- authorize to use groupkey
* add custom diff reporter DiffReporter that reports only paths that have a difference
* create Diff method for AlertRule that returns DiffReport, which is an alias for []Diff
Tests:
* create copy method for AlertRule in testing
* create GenerateAlertQuery method in testing
* Update API controller
- add validation of rules API model
- add function to calculate changes between the submitted alerts and existing alerts
- update RoutePostNameRulesConfig to validate input models, calculate changes and apply in a transaction
* Update DBStore
- delete unused storage method. All the logic is moved upstream.
- upsert to not modify fields of new by values from the existing alert
- if rule has UID do not try to pull it from db. (it is done upstream)
* Add rule generator
