AccessControl: Team membership migration (#44065)

Co-authored-by: ievaVasiljeva <ieva.vasiljeva@grafana.com>
Co-authored-by: Jguer <joao.guerreiro@grafana.com>

pkg/services/sqlstore/migrations/accesscontrol/errors.go

@@ -0,0 +1,17 @@
+package accesscontrol
+
+import "fmt"
+
+var ErrAddTeamMembershipMigrations = fmt.Errorf("Error migrating team memberships")
+
+type ErrUnknownRole struct {
+	key string
+}
+
+func (e *ErrUnknownRole) Error() string {
+	return fmt.Sprintf("%v: Unable to find role in map: %s", ErrAddTeamMembershipMigrations, e.key)
+}
+
+func (e *ErrUnknownRole) Unwrap() error {
+	return ErrAddTeamMembershipMigrations
+}