Use StyleCop.Analyzers to enforce code style/quality

[lbussell]

Currently there are no enforced rules as to code quality or style in any of the .NET Docker repos. We should consider using StyleCop.Analyzers to enforce consistency within and across projects. We can share the StyleCopAnalyzers.ruleset and stylecop.json across repos in the eng/common directory and reference it from each .csproj.

[dotnet-issue-labeler[bot]]

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[mthalman]

[Triage]

There's already this existing config file: https://github.com/dotnet/docker-tools/blob/main/.editorconfig. But that may only be supported by VS. The use of StyleCop.Analyzers is a more modern solution for handling this.