Add changes to bring up Keystore Certificate post processor.

Adds a system property which denotes the presence of a post processor.
Also adds the policies for the post processor service that is needed for
the processor to work correctly.

Test: manual check with test cert processor.
Bug: 361877215
Change-Id: I5feb0a250e2856189d5b4165187dcb415790e529
diff --git a/private/service.te b/private/service.te
index a4d00f3..1f31477 100644
--- a/private/service.te
+++ b/private/service.te
@@ -22,6 +22,7 @@
 type resolver_service,               system_server_service, service_manager_type;
 type rkpd_registrar_service,         service_manager_type;
 type rkpd_refresh_service,           service_manager_type;
+type rkp_cert_processor_service,     service_manager_type;
 type safety_center_service,          app_api_service, system_api_service, system_server_service, service_manager_type;
 type stats_service,                  service_manager_type;
 type statsbootstrap_service,         system_server_service, service_manager_type;