Revert "Move PlainDatagramSocketImpl away from JNI"

The PlainDatagramSocketImpl rewrite change set caused a regression in
casting device discovery mechanism. Revert these changes while
investigating the root cause.

This reverts the following commits:
77110aac1821ca512c3d2b05f2f6b1f5ab7091f6  DatagramSocket should set IP_MULTICAST_ALL to 0
0c38d180ead8b6d9bf3268979ac0967cb7e29283  Move PlainDatagramSocketImpl away from JNI (part 3)
0cda0594094f792c4ff923ea55311e0bd51a37c1  Move PlainDatagramSocketImpl away from JNI (part 2)
5e0df13532a902abc72c267a92bf3d83e71b0b1c  Move PlainDatagramSocketImpl away from JNI (part 1)

Test: Manual testing
Bug: 33957878
Change-Id: I3d27e642ab77cb01ba6f1eb619847f67b47e44d8
8 files changed