Access Control: Store permissions on SignedInUser (#43040)

* add permission structure to signedinuser

* add middleware to load user permissions into signedinuser struct

* apply LoadPermissionsMiddleware to http server

* check for permissions in signedinuser struct

Co-authored-by: Emil Tullstedt <emil.tullstedt@grafana.com>

pkg/models/user.go

@@ -183,6 +183,8 @@ type SignedInUser struct {
 	HelpFlags1     HelpFlags1
 	LastSeenAt     time.Time
 	Teams          []int64
+	// Permissions grouped by orgID and actions
+	Permissions map[int64]map[string][]string
 }
 
 func (u *SignedInUser) ShouldUpdateLastSeenAt() bool {