* 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
Yuriy Tseretyan
Jean-Philippe Quéméner