Make DiscoveryServer stream ID global

[smtilden]

[smtilden]

When surfacing V2 and V3 streams alongside each other in envoy-control,
DiscoveryServerCallbacks are unable to differentiate between V2 & V3 ADS
upon onStreamClose(), onStreamCloseWithError().

This means that any DiscoveryServerCallback that keeps state cannot pivot
on stream IDs, since there will be duplicate between V2 & V3. This change
creates a global StreamCounter, which ensures stream IDs will be unique
across V2 & V3 streams.

[codecov-io]

Codecov Report

Merging #157 (91da9e9) into master (ff834cb) will decrease coverage by 0.07%. The diff coverage is 75.00%.

@@             Coverage Diff              @@
##             master     #157      +/-   ##
============================================
- Coverage     88.22%   88.15%   -0.08%     
- Complexity      298      300       +2     
============================================
  Files            31       32       +1     
  Lines           977      979       +2     
  Branches         78       78              
============================================
+ Hits            862      863       +1     
- Misses           85       86       +1     
  Partials         30       30              

Impacted Files	Coverage Δ	Complexity Δ
.../envoyproxy/controlplane/server/StreamCounter.java	66.66% <66.66%> (ø)	2.00 <2.00> (?)
...nvoyproxy/controlplane/server/DiscoveryServer.java	100.00% <100.00%> (ø)	6.00 <3.00> (ø)

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[slonka]

I will look at it tomorrow, if you're in a hurry then go for it.

[slonka]

@jakubdyszkiewicz do you want to release it or should I?

[mpuncel]

@slonka looks like we should probably merge this? is your approval still good?

[slonka]

@mpuncel - yeah 👍 - I just did not release it because the release process was broken at the time. If it's fixed then go ahead.