AlertingNG: Modify queries and transform endpoint to get datasource UIDs (#30297)

* Pass skipCache from context

* Use macaron Params instead of ParamsEscape for UIDs

* Modify queries and transform to get datasource UIDs

* Update github.com/grafana/grafana-plugin-sdk-go to v0.83.0

pkg/expr/service.go

@@ -14,6 +14,10 @@ const DatasourceName = "__expr__"
 // expression command.
 const DatasourceID = -100
 
+// DatasourceUID is the fake datasource uid used in requests to identify it as an
+// expression command.
+const DatasourceUID = "-100"
+
 // Service is service representation for expression handling.
 type Service struct {
 }