Add file_contexts for sepolicy mainline module

Test: m com.android.sepolicy
Bug: 202394777
Change-Id: I6d11c693463206632237de1c4042845153fd6415
diff --git a/apex/com.android.sepolicy-file_contexts b/apex/com.android.sepolicy-file_contexts
new file mode 100644
index 0000000..83b4b58
--- /dev/null
+++ b/apex/com.android.sepolicy-file_contexts
@@ -0,0 +1 @@
+(/.*)?                   u:object_r:system_file:s0