Add type and mapping for /metadata/sepolicy

Test: make -j; launch_cvd; adb shell ls -laZ /metadata
Bug: 199914227
Change-Id: I573af0949d92f401589238dab8c3e9fbe2ee7efe
diff --git a/private/file_contexts b/private/file_contexts
index e7045e0..1079dca 100644
--- a/private/file_contexts
+++ b/private/file_contexts
@@ -778,6 +778,7 @@
 /metadata/password_slots(/.*)?    u:object_r:password_slot_metadata_file:s0
 /metadata/ota(/.*)?       u:object_r:ota_metadata_file:s0
 /metadata/bootstat(/.*)?  u:object_r:metadata_bootstat_file:s0
+/metadata/sepolicy(/.*)?    u:object_r:sepolicy_metadata_file:s0
 /metadata/staged-install(/.*)?    u:object_r:staged_install_file:s0
 /metadata/userspacereboot(/.*)?    u:object_r:userspace_reboot_metadata_file:s0
 /metadata/watchdog(/.*)?    u:object_r:watchdog_metadata_file:s0