Provide a easy way to access bpf maps from java

A wrapper for bpf map opening, reading/writing, and iteration.

Bug: 173167302
Test: atest BpfMapTest

Change-Id: I792b41978b322c9e4969cd7b6c35d6978ab86bc4
diff --git a/Tethering/jarjar-rules.txt b/Tethering/jarjar-rules.txt
index 591861f..d1ad569 100644
--- a/Tethering/jarjar-rules.txt
+++ b/Tethering/jarjar-rules.txt
@@ -8,4 +8,7 @@
 rule android.net.shared.Inet4AddressUtils* com.android.networkstack.tethering.shared.Inet4AddressUtils@1
 
 # Classes from net-utils-framework-common
-rule com.android.net.module.util.** com.android.networkstack.tethering.util.@1
\ No newline at end of file
+rule com.android.net.module.util.** com.android.networkstack.tethering.util.@1
+
+# Classes from net-utils-device-common
+rule com.android.net.module.util.Struct* com.android.networkstack.tethering.util.Struct@1