Mark System.Data.SqlClient as actually deprecated on NuGet

[ErikEJ]

https://www.nuget.org/packages/System.Data.SqlClient is not really marked as a deprecated NuGet package - to enhance the recent messaging to move to MDS, maybe it should be?

Example of a deprecated Nuget package: https://www.nuget.org/packages/ErikEJ.EntityFramework.SqlServer

Related blog post: https://techcommunity.microsoft.com/blog/sqlserver/why-it%E2%80%99s-time-to-migrate-from-system-data-sqlclient-to-microsoft-data-sqlclient/4406232

[cheenamalhotra]

Hi @ErikEJ

We are working towards that, but thanks for the feedback!