Add support for timeouts in asio/server

[moralismercatus]

This is an addition only. It does not change any existing functionality.
Server::open_connection_wait() is given an overload that takes a time
duration. The connection attempt will abort if not made within the given
time.

[likebreath]

@moralismercatus Thanks for the PR.

Have you run regression test on this change?

And what is the plan for fixing the problem of using Server::open_connection_wait() without timeout? I am assuming you are only adding a new Server::open_connection_wait() with timeout, but it is not being used. Please correct me if I misunderstood it.

[moralismercatus]

I have successfully compiled it on guest and host. As it doesn't effect the functionality, I didn't run any regression tests.

You are correct. The new function is not being used.

There are a few places where the new function needs to be used. In fact, I believe it should replace all existing open_connect_wait() calls. I'll have that implemented soon. I'd like to have this addition as a separate PR, so I can get more familiar with the process.