API compatibility validation improvements, DotNet

[BruceHaley]

Fixes #minor

Description

Task 'Verify publish compat results success' is now redundant. It compensated for a bug in the 'Publish compat results to GitHub' task which has been fixed.

Fix API validation to download all packages for both the contract and the implementation: Presence of the dependent packages for both gets more accurate validating. (For example, the assembly:TypeForwardedTo statement is then supported.)

Specific Changes

• Remove task 'Verify publish compat results success'.
• Fix download to get all packages for API compare. (Readme does not explain how interdependent assembly handling affects ApiCompat reporting accuracy dotnet/arcade#9725).
• Add task 'Publish compat results to Artifacts'. This makes results more accessible to forks, as they are not published to forked PRs.
• Add file ApiCompatBaseline.txt. This replaces the functionality of the var ApiCompatExcludeClasses, with the added benefit of allowing API validation to succeed (go green) instead of always showing partial success.
• Tweak var names and display names for readability.

[coveralls]

Pull Request Test Coverage Report for Build 324149

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 13 unchanged lines in 5 files lost coverage.
• Overall coverage decreased (-0.04%) to 79.073%

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Files with Coverage Reduction	New Missed Lines	%
/libraries/AdaptiveExpressions/BuiltinFunctions/GetNextViableTime.cs	1	90.91%
/libraries/AdaptiveExpressions/BuiltinFunctions/GetPreviousViableTime.cs	1	90.91%
/libraries/Microsoft.Bot.Connector.Streaming/TaskExtensions.cs	1	82.61%
/libraries/Microsoft.Bot.Connector.Streaming/Transport/TransportHandler.cs	2	96.39%
/libraries/Microsoft.Bot.Connector.Streaming/Session/StreamingSession.cs	8	89.62%

Totals
Change from base Build 324121:	-0.04%
Covered Lines:	25580
Relevant Lines:	32350

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💛 - Coveralls