Evaluate data stall via tcp signal

Allow NetworkStack to send SockDiag netlink request and parse
returned tcp info. Evaluate the internet health from the tcp
information.

Bug: 136162280
Test: atest NetworkStackTests NetworkStackNextTests
Test: Use "adb shell ss" command to check the parsing info
Change-Id: I8df0d11c748c95d3a57115ebb6a4e29d8b50f177

• src/android/net/util/DataStallUtils.java[diff]
• src/com/android/networkstack/netlink/TcpSocketTracker.java[Added - diff]
• src/com/android/server/connectivity/NetworkMonitor.java[diff]
• tests/unit/src/com/android/networkstack/netlink/TcpSocketTrackerTest.java[Added - diff]
• tests/unit/src/com/android/server/connectivity/NetworkMonitorTest.java[diff]