[Shiny] Compatibility issues with Shiny v2.0+

[JeremyBP]

Shiny v2.0 removed built in caching feature. It also introduced a reshaped logging feature relying on Microsoft.Extensions.Logging.

Workaround: Don't call .UseWhatever(...) from Shiny intergration package anymore but .AddWhatever(...) instead and set options fluently like caching and logging providers.

Fix: I'm working on a new release relying on Microsoft.Extensions.Logging.Abstraction to get things less specific/more generic, just like Shiny does. Caching feature should now be activated fluently with the provider of your choice (e.g. MonkeyCache or Akavache).

[JeremyBP]

Removed from v4