add tests to sync classes

[roywanyaga]

IMPORTANT: All PRs must be linked to an issue (except for extremely trivial and straightforward changes).

Description
Add tests to engine module sync classes:

• sync/download/ResourceParamsBasedDownloadWorkManager
• sync/upload/BundleUploader
• sync/upload/TransactionBundleGenerator

Alternative(s) considered
N/A

Type
Testing

Screenshots (if applicable)

Checklist

• I have read and acknowledged the Code of conduct.
• I have read the Contributing page.
• I have signed the Google Individual CLA, or I am covered by my company's Corporate CLA.
• I have discussed my proposed solution with code owners in the linked issue(s) and we have agreed upon the general approach.
• I have run ./gradlew spotlessApply and ./gradlew spotlessCheck to check my code follows the style guide of this project.
• I have run ./gradlew check and ./gradlew connectedCheck to test my changes locally.
• I have built and run the demo app(s) to verify my change fixes the issue and/or does not break the demo app(s).

[codecov]

Codecov Report

Merging #1505 (d39d9df) into master (87c3437) will increase coverage by 74.84%.
The diff coverage is n/a.

❗ Current head d39d9df differs from pull request most recent head 9c2cef6. Consider uploading reports for the commit 9c2cef6 to get more accurate results

@@              Coverage Diff              @@
##             master    #1505       +/-   ##
=============================================
+ Coverage          0   74.84%   +74.84%     
- Complexity        0      663      +663     
=============================================
  Files             0      128      +128     
  Lines             0     3995     +3995     
  Branches          0      726      +726     
=============================================
+ Hits              0     2990     +2990     
- Misses            0      611      +611     
- Partials          0      394      +394     

see 128 files with indirect coverage changes

[omarismail94]

@roywanyaga can you update this PR to merge the changes in master, resolving any conflict? It should get merged once it passes the tests we have

[jingtang10]

I tidied this PR up - @omarismail94 can you take a look please? Thanks!