Add file contexts for FederatedCompute.

Test: TH
Change-Id: If302dc80a5be0b72e417698a60a92a05bedde8a1
diff --git a/apex/com.android.federatedcompute-file_contexts b/apex/com.android.federatedcompute-file_contexts
new file mode 100644
index 0000000..9398505
--- /dev/null
+++ b/apex/com.android.federatedcompute-file_contexts
@@ -0,0 +1 @@
+(/.*)?           u:object_r:system_file:s0