#2057 FetcherBolt: extract the response and failure handling

[dpol1]

Moves the mapping from response or exception to status, stream and metadata
to FetchOutcomes, with unit tests. Emits, acks and the finally stay in
FetcherThread. The exception counter is now incremented just before the emit.

Part of #2057.

[jnioche]

I think we should have a sub package for all the things extracted from FetcherBolt, like o.a.s.fetcher
There should only be bolt classes in o.a.s.bolt. This is an important package, we want to keep things tidy and not have tons of stuff without much structure

[dpol1]

Good point @jnioche. If i make a dedicated package I'd have to make em public - is that a trade off we want? Just a quick question for now, I'll investigate more later

[rzo1]

I think it wouldn't be a problem if the Javadoc states, that those classes are intendent for internal use only ;-)

[dpol1]

sounds good to me @rzo1, thank you 👍 - I'll proceed right away adding another PR to the stack

[dpol1]

I think we should have a sub package for all the things extracted from FetcherBolt, like o.a.s.fetcher There should only be bolt classes in o.a.s.bolt. This is an important package, we want to keep things tidy and not have tons of stuff without much structure

see #2209

Package extraction was done.