Explore: Add transformations to correlation data links (#61799)

* bring in source from database

* bring in transformations from database

* add regex transformations to scopevar

* Consolidate types, add better example, cleanup

* Add var only if match

* Change ScopedVar to not require text, do not leak transformation-made variables between links

* Add mappings and start implementing logfmt

* Add mappings and start implementing logfmt

* Remove mappings, turn off global regex

* Add example yaml and omit transformations if empty

* Fix the yaml

* Add logfmt transformation

* Cleanup transformations and yaml

* add transformation field to FE types and use it, safeStringify logfmt values

* Add tests, only safe stringify if non-string, fix bug with safe stringify where it would return empty string with false value

* Add test for transformation field

* Do not add null transformations object

* Break out transformation logic, add tests to backend code

* Fix lint errors I understand 😅

* Fix the backend lint error

* Remove unnecessary code and mark new Transformations object as internal

* Add support for named capture groups

* Remove type assertion

* Remove variable name from transformation

* Add test for overriding regexes

* Add back variable name field, but change to mapValue

* fix go api test

* Change transformation types to enum, add better provisioning checks for bad type name and format

* Check for expression with regex transformations

pkg/services/correlations/database.go

@@ -129,6 +129,9 @@ func (s CorrelationsService) updateCorrelation(ctx context.Context, cmd UpdateCo
 			if cmd.Config.Target != nil {
 				correlation.Config.Target = *cmd.Config.Target
 			}
+			if cmd.Config.Transformations != nil {
+				correlation.Config.Transformations = cmd.Config.Transformations
+			}
 		}
 
 		updateCount, err := session.Where("uid = ? AND source_uid = ?", correlation.UID, correlation.SourceUID).Limit(1).Update(correlation)