Add cancellation tokens to methods that have a parameter but we don't pass

[rjmurillo]

Most often this was while getting the type information from the semantic model. In cases where the asynchronous operation is cancelled, the underlying calls would not be aborted because we did not propagate forward the cancellation token. This was not picked up by analyzer CA2016 because the cancellation token is not provided on the method used by DiagnosticAnalyzer, but rather on the SyntaxNodeAnalysisContext instance passed in.

The issue was corrected by adding a new analyzer package and enabling an analyzer rule within that package. Both rules are set to error in .editorconfig to avoid introducing new code with this issue

Fixes #43

[MattKotsenas]

Left a single comment about lifting code analysis packages into a build slice. Also happy to do that as a follow up change (if so, file an issue).

Thanks!