[v9.3.x] SSE: Make sure to forward headers, user and cookies/OAuth token (#59390)

SSE: Make sure to forward headers, user and cookies/OAuth token (#58897)

Fixes #58793 and Fixes https://github.com/grafana/azure-data-explorer-datasource/issues/513

Co-authored-by: Marcus Efraimsson <marcus.efraimsson@gmail.com>
(cherry picked from commit 5623b5afaf)

Co-authored-by: Kyle Brandt <kyle@grafana.com>

pkg/expr/transform.go

@@ -35,14 +35,19 @@ type Request struct {
 	Debug   bool
 	OrgId   int64
 	Queries []Query
+	User    *backend.User
 }
 
+// QueryDataRequestEnricher function definition for enriching a backend.QueryDataRequest request.
+type QueryDataRequestEnricher func(ctx context.Context, req *backend.QueryDataRequest) context.Context
+
 // Query is like plugins.DataSubQuery, but with a a time range, and only the UID
 // for the data source. Also interval is a time.Duration.
 type Query struct {
 	RefID         string
 	TimeRange     TimeRange
 	DataSource    *datasources.DataSource `json:"datasource"`
+	QueryEnricher QueryDataRequestEnricher
 	JSON          json.RawMessage
 	Interval      time.Duration
 	QueryType     string