Analyzer to err when referencing virtual members in constructor of defining class

In reference to PR https://github.com/Azure/azure-sdk/pull/1888 for the [reiterated requirement to note reference virtual members of the class defining the constructor](https://azure.github.io/azure-sdk/dotnet_introduction.html#dotnet-client-constructor-use-params), we should have an analyzer that errs when you do this. Maybe it could see if there's a corresponding parameter (or if one was used to set the property), but at least erring calls attention to fixing this issue.

Start by reading PR 1888 and the linked .NET constructor guidance to establish the required behavior, then locate the analyzer implementation and its existing tests. Done means the analyzer reliably reports references to virtual members from the defining class's constructor, with coverage for the supported constructor patterns.

Written by the indexing model from the issue text.