Auth: Move access control API to SignedInUser interface (#73144)

* move access control api to SignedInUser interface

* remove unused code

* add logic for reading perms from a specific org

* move the specific org logic to org_user.go

* add a comment

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Co-authored-by: IevaVasiljeva <ieva.vasiljeva@grafana.com>

pkg/services/auth/identity/requester.go

@@ -53,6 +53,8 @@ type Requester interface {
 
 	// Legacy
 
+	// HasRole returns true if the active entity has the given role in the active organization.
+	HasRole(role roletype.RoleType) bool
 	// GetCacheKey returns a unique key for the entity.
 	// Add an extra prefix to avoid collisions with other caches
 	GetCacheKey() (string, error)