Debugging log for Daemons and Handlers.

[YooSunYoung]

Message constructor should be with the generator(daemon or handler) rather than the receiver(only handler).

Since we are using Protocol, handlers and daemons don't have to know about each other.
So it only makes sense to keep the Message constructor with the daemon or handler that produces it.
For example,
beamlime.applications.daemons.DataStreamSimulator generates RawMessageSent,
and beamlime.applications.handlers.DataReductionHandler receives it.
So RawMessageSend should rather be in beamlime.applications.daemons, not in beamlime.applications.handlers if not somewhere else.

try-except instead of hasattr.

Some Handlers had to initialize its status according to the first message it processes.
In that case, it is better to use try-except, i.e. with AttributeError,
so that the first-message check doesn't cost anything.

AsyncGenerator.asend didn't make first-message processing easier.

It was very messy after-all since the first asend call should be called with None.
Then it needs try-exception anyways and it made type-hint very messy.
It was better to stick to the try-except...