Move attach*Filter() and addArpEntry() methods to NetworkStack

The SocketUtils.attach*Filter and SocketUtils.addArpEntry methods
were added there because they could not be added as JNI inside
the NetworkStack. This was not possible because on Go devices,
the NetworkStack was a jar library. But now, Go also uses an APK.
Hence, move these methods to the NetworkStack.

Fixes: 129433183
Merged-In: I66d7b3e4fbfa32bb0bc853e8cf9399031daff8a9
(cherry picked from commit fe71be2b)

Change-Id: Ice433a41469e784385f19498c154345d7b9c69b5