Migrate netlink-client to net-utils-device-common-netlink.

Move netlink stuff to frameworks/libs/net/common/device, and build the
source files as an individual libraray. NetworkStack module just depends
on the net-utils-device-common-netlink.

Besides, also fix the incorrect format detected by checkstyle_hook script
such as missing java doc and make some public function as private, rename
the variable and etc.

Bug: 192535368
Test: atest NetworkStaticlibTests
Change-Id: I00e7f30be1bc9ebc2e24d7cd53efc403d6ba3daa
diff --git a/staticlibs/testutils/Android.bp b/staticlibs/testutils/Android.bp
index 6d9414f..89aa136 100644
--- a/staticlibs/testutils/Android.bp
+++ b/staticlibs/testutils/Android.bp
@@ -32,6 +32,7 @@
         "libnanohttpd",
         "net-tests-utils-host-device-common",
         "net-utils-device-common",
+        "net-utils-device-common-netlink",
         "modules-utils-build_system",
     ],
 }