Enforce NuGet package validations as part of the build

[baronfel]

NuGet Package Explorer has validations for

• valid signatures
• Sourcelink enablement
• Deterministic builds
• compiler flags accessible

It could be a good enhancement if those things were validated for built packages and apps as part of this package.

[MattKotsenas]

I like the idea, though I think I'm less of a fan of packaging NuGet Package Explorer as part of this package?

I could however get behind something like a set of BuildChecks (or enabling a set of BuildChecks defined elsewhere)