Replace signed in user for identity.requester (#73750)

* Make identity.Requester available at Context

* Clean pkg/services/guardian/guardian.go

* Clean guardian provider and guardian AC

* Clean pkg/api/team.go

* Clean ctxhandler, datasources, plugin and live

* Question: what to do with the UserDisplayDTO?

* Clean dashboards and guardian

* Remove identity.Requester from ReqContext

* Implement NewUserDisplayDTOFromRequester

* Fix tests

* Change status code numbers for http constants

* Upgrade signature of ngalert services

* log parsing errors instead of throwing error

* Fix tests and add logs

* linting

pkg/services/folder/model.go

@@ -5,6 +5,7 @@ import (
 	"time"
 
 	"github.com/grafana/grafana/pkg/infra/slugify"
+	"github.com/grafana/grafana/pkg/services/auth/identity"
 	"github.com/grafana/grafana/pkg/services/user"
 	"github.com/grafana/grafana/pkg/setting"
 	"github.com/grafana/grafana/pkg/util/errutil"
@@ -138,6 +139,7 @@ type GetFolderQuery struct {
 	OrgID int64
 
 	SignedInUser *user.SignedInUser `json:"-"`
+	Requester    identity.Requester `json:"-"`
 }
 
 // GetParentsQuery captures the information required by the folder service to