IAsyncActionFilter for asp.net core signalR

[Edward-Zhou]

Is your feature request related to a problem? Please describe.

For Asp.Net Core MVC, we could try IAsyncActionFilter to capture the action event and to calculate the action hanlding time, or handle something before and after processing the action.

For signalr, it supports OnConnectedAsync and OnDisconnectedAsync for connection event which will fire when connection start and disconnect.

I am wondering whether there is a similar functionality like actionfiler in aspnetcore, and then we could custom the lifecycle to do something before and after the action executes

[davidfowl]

Dupe of #5353. We don't have this yet but it's planned for a future release.