Fix concurrency bug in Replay

[jacksoncheek]

JIRA

https://compass-tech.atlassian.net/browse/CEI-504

Summary

• Replay has a concurrency bug. When multiple subscribers are posting values to it from different threads, we can hit an index out of bounds exception.
• This is causing a semi-major bug in the offline banner feature on Android.
• Adds a test (that breaks without the changes) and fixes Replay by adding concurrency locks around the internal values list.

Stacktrace

Fatal Exception: java.lang.ArrayIndexOutOfBoundsException: length=2; index=2
       at java.util.ArrayList.add(ArrayList.java:468)
       at com.compass.snail.Replay.next(Replay.kt:17)
       at com.compass.snail.Variable.setValue(Variable.kt:18)
       at com.compass.compasslibrary.services.NetworkBroadcastReceiverService.updateConnection(NetworkBroadcastReceiverService.kt:42)
       at com.compass.compasslibrary.apiv3.ModelRequest$request$1$2.onFailure(ModelRequest.kt:59)
       at com.google.firebase.perf.network.zzf.onFailure(com.google.firebase:firebase-perf@@18.0.1:18)
       at okhttp3.RealCall$AsyncCall.execute(RealCall.java:161)
       at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32)
       at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
       at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
       at java.lang.Thread.run(Thread.java:764)

[codecov]

Codecov Report

Merging #43 into master will increase coverage by 0.21%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #43      +/-   ##
==========================================
+ Coverage   86.93%   87.15%   +0.21%     
==========================================
  Files          17       17              
  Lines         176      179       +3     
  Branches       14       14              
==========================================
+ Hits          153      156       +3     
  Misses         18       18              
  Partials        5        5

Impacted Files	Coverage Δ
...l-kotlin/src/main/java/com/compass/snail/Replay.kt	100% <100%> (ø)	⬆️

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[jacksoncheek]

Reverting from queue data structure, our Rx framework supports null items and the thread-safe LinkedBlockingQueue in the Java concurrent util package does not.