Fix issue#9807 2nd draft (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 95.90121% with 78 lines in your changes missing coverage. Please review.

Project coverage is 75.87018%. Comparing base (cac5a6c) to head (c687aa1).

Additional details and impacted files

@@                 Coverage Diff                 @@
##                main      #12489         +/-   ##
===================================================
+ Coverage   75.75486%   75.87018%   +0.11532%     
===================================================
  Files           3159        3163          +4     
  Lines         635942      637684       +1742     
  Branches       46987       47061         +74     
===================================================
+ Hits          481757      483812       +2055     
+ Misses        150726      150410        -316     
- Partials        3459        3462          +3     

Flag	Coverage Δ
Debug	75.87018% <95.90121%> (+0.11532%)	⬆️
integration	18.15291% <0.00000%> (-0.02577%)	⬇️
production	49.49607% <85.55556%> (+0.17887%)	⬆️
test	97.05725% <100.00000%> (+0.01133%)	⬆️
unit	46.72632% <85.55556%> (+0.19532%)	⬆️

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[paul1956]

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