Set isConnected, isBound, implCreated on server-side LocalSockets

Previously LocalServerSocket.accept() would return a LocalSocket
instance with isConnected, isBound and implCreated set to false.
[implCreated determines whether impl.create() needs to called].

A socket created via accept() in this way is implicitly bound
and connected. impl.create() does not need to be called because
impl.accept(LocalSocketImpl s) is called instead and has the same
effect (s.fd and s.mFdCreatedInternally set correctly).

This change modifies the behavior so that the flags are now all
set to true in this case and isBound() and isConnected() will
now return the correct answer.

Attempts to call bind() and connect() will still throw
IOException as before, but with a different exception message.

Correctly setting implCreated in LocalSocket means that
LocalSocketImpl.create() will no longer be called for accept()
created sockets and no longer needs to treat the "fd != null"
case as a no-op: we can now assert that there must be no fd set
when create() is called as we will no longer call it with sockets
created using accept().

Bug: https://code.google.com/p/android/issues/detail?id=35942
Test: Device boot
Test: vogar --mode app_process cts/tests/tests/net/src/android/net/cts/LocalServerSocketTest.java
Test: vogar --mode app_process cts/tests/tests/net/src/android/net/cts/LocalSocketTest.java
Change-Id: I3ac55439412e84501ae7c5ae6c9976e03b2d6fc5