Add NuGet package groupings to Renovate Bot config (#687)
Add NuGet package groupings to Renovate Bot config (#687)

Adds the following (separate) groupings:
- All packages from @Taritsyn's JavascriptEngineSwitcher repo
- All packages from https://github.com/aspnet/Extensions
- `Microsoft.AspNetCore*` packages plus those with source repo https://github.com/aspnet/MetaPackages or https://github.com/aspnet/AspNetCore
- `Microsoft.Owin*` packages
reactjs/React.NET,reactjs/React.NET,reactjs/React.NET,reactjs/React.NET,reactjs/React.NET,reactjs/React.NET