Fix SocketUtils API

 - connect, sendTo, bind were added as public API, so do not need to be
   maintained as SystemApi in SocketUtils. These APIs were added in Q
   timeframe.
 - Add @Nullable/@NonNull annotations.

Bug: 126699304
Bug: 126477266
Test: booted, WiFi works
Change-Id: I3f086ac8952cfd6a4d8f861d2e1c7aa1ca8be999
8 files changed