Add sepolicy for com.android.sdkext module

Bug: 137191822
Test: m com.android.sdkext
Change-Id: Ia5fb99af7fad43ce4321b1c6611ab54340a87589
diff --git a/apex/com.android.sdkext-file_contexts b/apex/com.android.sdkext-file_contexts
new file mode 100644
index 0000000..f3a65d4
--- /dev/null
+++ b/apex/com.android.sdkext-file_contexts
@@ -0,0 +1 @@
+(/.*)?                u:object_r:system_file:s0