Consolidate general-purpose analyzers in Microsoft.AspNetCore.Analyzers

[rynowak]

We've added analyzers that support the ASP.NET Core startup experience and a few more general ASP.NET Core features. Right now these live in the Microsoft.AspNetCore.Mvc.Analyzers package which isn't the right place.

When users look at this in the VS UI they would be confused, this also affects how they get represented in .ruleset files. We can save people some pain by getting the branding of this right in 3.0 (none of this shipped in previous versions).

• Consolidate general-purpose analyzers #12289 Move analyzers into this the right places
• Adds Microsoft.AspNetCore.Analyzers package websdk#789 Add M.A.Analyzers to the WebSDK