SSLSocket should respect timeout of a wrapped Socket

SSLSocket should respect timeout of a wrapped Socket

Change to using getSoTimeout in OpenSSLSocketImpl instead of directly
using the timeout field. This means the proper timeout will be used
for instances of the OpenSSLSocketImplWrapper subclass, which is used
when an SSLSocket is wrapped around an existing connected non-SSL
Socket. The code still maintains the local timeout field, now renamed
timeoutMilliseconds, which is now accesed via
OpenSSLSocketImpl.getSoTimeout. Doing so prevents a getsockopt syscall
that otherwise would be necessary if the super.getSoTimeout() was used.

Added two unit tests for testing timeouts with SSLSockets wrapped
around Socket. One is simply for getters/setters. The second makes
sure the timeout is functioning when set on the underlying socket.

Bug: 2973305
Change-Id: Idac52853f5d777fae5060a840eefbfe85d448e4c