Deliver each event in a separate request to avoid exceeding payload size limit

[fractalwrench]

Goal

The payload size limit can be exceeded if multiple events are batched together into one request, meaning events are dropped by our API. This changeset removes the batching functionality and sends each event in a separate request to reduce the likelihood of this occurring.

Changeset

• Sent each event in a separate request within sendAllReportsWithCompletion.
• Logged the filename when a request succeeds/fails
• Passed through 1 event at a time to BugsnagApiClient for errors (sessions are still batched together in multiple payloads)
• Changed completion callback to send the filename rather than the count of reports sent

Tests

• Stored multiple events on disk, then launched the notifier configured to point at a local endpoint and confirmed that each request was received individually.
• Updated mazerunner scenario assertions where they assumed requests were batched

[codecov]

Codecov Report

Merging #424 into next will decrease coverage by 0.22%.
The diff coverage is 18.6%.

@@            Coverage Diff             @@
##             next     #424      +/-   ##
==========================================
- Coverage   52.79%   52.56%   -0.23%     
==========================================
  Files          66       66              
  Lines        7594     7590       -4     
==========================================
- Hits         4009     3990      -19     
- Misses       3585     3600      +15

Impacted Files	Coverage Δ
...SCrash/Recording/Tools/BSG_KSCrashCallCompletion.m	100% <100%> (ø)	⬆️
Source/BugsnagErrorReportApiClient.m	86.66% <50%> (ø)	⬆️
...rce/KSCrash/Source/KSCrash/Recording/BSG_KSCrash.m	48.16% <50%> (-1.84%)	⬇️
Source/BugsnagSink.m	12.08% <6.25%> (-7.27%)	⬇️
Source/BugsnagFileStore.m	66.19% <0%> (-3.34%)	⬇️

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[kattrali]

Thanks for looking into this. This changeset handles many of the cases involved in report delivery, however, I can't merge it as-is since there are a few architectural problems to address.

1. As far as I've been able to tell, reports that are cancelled via beforeSend/beforeNotify blocks are never deleted now, unless enough new reports are added that they are removed due to file count limits. It could mean hanging around forever.
2. The naming of the functions and parameters around delivery are often not logically consistent. Some specify plurals where they are now used for single items, others specify "completion" where the block is called many times. In addition, someof the documentation for the blocks no longer match so its not clear where the error lies for future passersby.

Neither of these are hard problems, however it looks like a good candidate for taking a step back and making a more detailed plan for the changes. Rather than going through each change inline, I'll sketch out something to work with. The tests are an excellent scaffold for ensuring that the end result is right, with some additions to ensure that cancelled files are deleted.

[fractalwrench]

Closing as stale.