Add package vulnerability information

[MichelZ]

AI Blurp

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This pull request includes changes to the NuGet configuration and build properties to improve package source auditing and manage warnings more effectively. The most important changes are as follows:

NuGet Configuration Updates:

• NuGet.config: Added an auditSources section to specify sources for auditing, including nuget.org as an audit source.

Build Properties Enhancements:

• src/Directory.Build.props: Introduced a WarningsNotAsErrors property to exclude specific warnings from being treated as errors.
• src/Directory.Build.props: Added a NuGetAuditMode property to enable auditing for all package sources.

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Description

Adding new functionality for .NET 9 / VS 17.12 / NuGet 6.12 with Audit Sources.
Also adding that the vulnerabilities (currently) are not treated as errors, but this can of course be enabled in the future

The idea is that package vulnerabilities get visibility at least on a warning level everywhere.
I'm sure I don't have to remind anyone of this, but I still do 😁 :
https://blogs.microsoft.com/blog/2024/05/03/prioritizing-security-above-all-else/

If you’re faced with the tradeoff between security and another priority, your answer is clear: Do security. -- Satya Nadella

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 72.73%. Comparing base (1b9df10) to head (0213a45).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3024      +/-   ##
==========================================
+ Coverage   72.64%   72.73%   +0.08%     
==========================================
  Files         285      285              
  Lines       59160    59160              
==========================================
+ Hits        42979    43028      +49     
+ Misses      16181    16132      -49     

Flag	Coverage Δ
addons	92.58% <ø> (ø)
netcore	75.46% <ø> (+0.07%)	⬆️
netfx	71.13% <ø> (+0.04%)	⬆️

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[MichelZ]

Also related to #2568