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.te b/private/file.te
index f2d3f56..f3e1855 100644
--- a/private/file.te
+++ b/private/file.te
@@ -74,3 +74,6 @@
 
 # /apex/com.android.virt/bin/fd_server
 type fd_server_exec, system_file_type, exec_type, file_type;
+
+# /metadata/sepolicy
+type sepolicy_metadata_file, file_type;