Stop coverlet clobbering dependencies

[ta264]

Expose coverlet.core as a package, and pull in dependencies like a normal nuget package.

This stops coverlet clobbering dependencies on publish.

• Fixes When publishing test project "CopyCoverletDataCollectorFiles" overwrites project assemblies #1131
• Fixes dotnet publish with test project leads to "Could not load file or assembly 'Microsoft.Extensions.FileSystemGlobbing, Version=3.1.0.0" #1106

[MarcoRossignoli]

At the moment we don't want to expose core lib as package, we discussed this one a lot of times, but for the moment we don't have a stable shape to expose. If we expose core as lib we want to do it in a proper stable way with a public "stable" contract.

[MarcoRossignoli]

We're not ready to expose coverlet.core as standalone package yet.
Here you can find some discussion about it, but we didn't reach a mature time/reason to do it yet.
Maybe we could move on the discussion #212
Did also some experiment here #628

[ta264]

Thanks for the comment. I don't really have a strong view about how this should be fixed but the current behaviour is pretty antisocial and should be changed in my opinion.

[MarcoRossignoli]

I'll keep this open for now as reminder of possibile solution. Thanks for the suggestion!

[MarcoRossignoli]

Worked a bit on this one and maybe I found a way to avoid override without expose core #1243

thanks for your investigation/proposal here!