Track tethering active sessions counts

This commit implements the necessary counters to bookkeep
max connection count, which will be used in follow-up changes
to monitor and upload active tethering session metrics.

The feature is disabled by default and will be gradually
rolled out.

Test: atest TetheringTests:com.android.networkstack.tethering.BpfCoordinatorTest
Bug: 354619988
Change-Id: Iaf251b0ec08bde95c1b12df022db2e03179309de
diff --git a/Tethering/Android.bp b/Tethering/Android.bp
index d04660d..498a1fe 100644
--- a/Tethering/Android.bp
+++ b/Tethering/Android.bp
@@ -54,6 +54,7 @@
         "src/**/*.java",
         ":framework-connectivity-shared-srcs",
         ":services-tethering-shared-srcs",
+        ":statslog-connectivity-java-gen",
         ":statslog-tethering-java-gen",
     ],
     static_libs: [