Implement a Analyzers similar to dotnet/runtime and use their ruleset

[elachlan]

dotnet/runtime has analyzers implemented to help reduce code issues and have put together a decent list of rules.

https://github.com/dotnet/runtime/blob/master/eng/CodeAnalysis.ruleset

I suggest the rules and the analyzers are duplicated here in msbuild to help enforce code style and reduce potential errors. It will also help make PRs higher quality, reducing the burden on reviewers for trivial issues.

We could have the rules set to "info" so they don't cause build failures. Then enable each rule one by one over time so that the changes are isolated to a PR/commit.

[cdmihai]

And it would cool to also have a formatter: #4092