Add a module with thread-safety and a flexible tipc user space API

The goal of this module are three folds:
1. the ability to share the handleset with the event loop as well as a
   service
2. removing the dispatcher from the event pipeline
3. make the user space constructs thread safe, so that they can be
   shared with the RPC binder services which has the thread safety
   requirement

This CL adds a trait to be implemented by the handle objects stored in
the CoreHandleSet in order to retrieve the raw fd. This simplifies the
API of CoreHandleSet.
This CL also cleans up the code of the new rust tipc library.

Test: aosp/3506455
Bug: 382291660
Change-Id: I2bf0a8e8bf1b235f89a76fc842356e0f4d668ee8