Fix issue#9807 review 2nd (Replaces PR #11867) DRAFT

[paul1956]

Fixes #9807

Proposed changes

• Add Remove dependance on WebClient for VB FileDownload by using HttpClient
• Upload still uses WebClient that also needs to be done as a separate PR

Customer Impact

• Adds Async file download support to VB, and if WebClient goes away this will allow existing Visual Basic programs using synchronous File Download to still work.
• It also enables Async FileDownload is API is approved

Regression?

• Yes, when WebClient if and when goes away, not today

Risk

• The existing code uses ICredentials in some of the paths, it is unclear how compatible that is between WebClient and HttpClient

• Close to 100% Code Coverage Before and After change, original tests had no tests and there Error Message handling was odd

• There are Exception Messages that need to move from WebClient to this PR and be translated.

Microsoft Reviewers: Open in CodeFlow

[codecov]

Codecov Report

Attention: Patch coverage is 94.72256% with 214 lines in your changes missing coverage. Please review.

Project coverage is 77.11603%. Comparing base (fbd28a7) to head (2f6a941).

Additional details and impacted files

@@                 Coverage Diff                 @@
##                main      #12489         +/-   ##
===================================================
+ Coverage   76.90985%   77.11603%   +0.20617%     
===================================================
  Files           3260        3270         +10     
  Lines         643088      646894       +3806     
  Branches       47601       47907        +306     
===================================================
+ Hits          494598      498859       +4261     
+ Misses        144830      144362        -468     
- Partials        3660        3673         +13     

Flag	Coverage Δ
Debug	77.11603% <94.72256%> (+0.20617%)	⬆️
integration	18.96574% <0.00000%> (-0.02879%)	⬇️
production	51.86075% <83.08458%> (+0.27853%)	⬆️
test	97.42366% <97.60074%> (+0.00213%)	⬆️
unit	49.25327% <83.08458%> (+0.29267%)	⬆️

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[paul1956]

@Tanya-Solyanik this PR should be DRAFT, please.