Changes:
* Upgrade dependencies and build tools
* Change TFM on Microsoft.AspNetCore.Routing packages to netcoreapp3.0
* Remove .NET Framework tests
* Remove the IL_EMIT conditional compilation because this assembly only targets .NET Core now.
For preview one the branding is:
new thing = UseGlobalRouting/UseEndpoint
old thing = UseRouter
We're going to drop the name Dispatcher everywhere and make sure that we
position our new work as 'new and improved routing' instead of
introducing a new product/concept name.
We're not totally sure of the term Global yet, but it's what we're doing
for preview 1. Suggestions welcome for dicussion after we do the first
preview :)