Fix callbacks for RestAPI

[bbirman]

Manually tested for now, I still want to see if we can add a unit/integration test for it

[bbirman]

This is the main change, use the callback on the individual request, otherwise the callback on one of the requests is used for all the requests

[wmathurin]

Was it a recent regression? Or was it always like that?

[bbirman]

I think it came in with #3862 in 13.1. That thread had a similar issue with replaying a request which I thought was fixed but the sample app doesn't exercise having different callbacks for each request so I think we missed this part of it

[codecov]

Codecov Report

❌ Patch coverage is 82.35294% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 61.37%. Comparing base (972e43e) to head (9f1264e).
⚠️ Report is 8 commits behind head on dev.

Files with missing lines	Patch %	Lines
...Core/SalesforceSDKCore/Classes/RestAPI/SFRestAPI.m	82.35%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #3958      +/-   ##
==========================================
- Coverage   63.85%   61.37%   -2.49%     
==========================================
  Files         252      255       +3     
  Lines       22111    22722     +611     
==========================================
- Hits        14120    13945     -175     
- Misses       7991     8777     +786     

Components	Coverage Δ
Analytics	70.78% <ø> (ø)
Common	70.23% <ø> (+0.46%)	⬆️
Core	51.34% <82.35%> (-3.40%)	⬇️
SmartStore	73.99% <ø> (-0.60%)	⬇️
MobileSync	87.41% <ø> (ø)

Files with missing lines	Coverage Δ
...Core/SalesforceSDKCore/Classes/RestAPI/SFRestAPI.m	86.63% <82.35%> (-0.97%)	⬇️

... and 17 files with indirect coverage changes

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[github-actions]

	1 Warning
⚠️	Static Analysis found an issue with one or more files you modified. Please fix the issue(s).

Clang Static Analysis Issues

File	Type	Category	Description	Line	Col
SFRestAPI	Nullability	Memory error	nil assigned to a pointer which is expected to have non-null value	98	5

Generated by 🚫 Danger

[bbirman]

For line 478, I saw an issue where the same request is being removed multiple times along with the callback being executed more than once (if the active queue is at least two requests), I'm thinking it's because flushPendingRequestQueue is synchronized to self but the removeObject call isn't.

The part I don't know the history on is why the failure block for first request was triggered separately, it looks like the same values are passed to the failure block whether it's called here or through flushPendingRequestQueue

[bbirman]

• Unit tests are passing locally (core, common, analytics, SmartStore & MobileSync)
• Added a test for scenario where refresh is successful and queue is replayed to make sure success block is only called once per request, also manually tested in RestAPIExplorer
• Manually tested scenario where refresh fails for issue where failure block was being called multiple times