SignalR - create Hub

[BekAllaev]

I suggest mark this issue as closed what do you think @SergeyDavidovich? We have this two hubs:

• Dashboard hub: https://github.com/SergeyDavidovich/OMSBlazor/blob/127696762f7fa748337642dce2418b90e6a21092/src/OMSBlazor.NotificationSender/Signalr/Hubs/DashboardHub.cs#L12
• Product hub: https://github.com/SergeyDavidovich/OMSBlazor/blob/127696762f7fa748337642dce2418b90e6a21092/src/OMSBlazor.NotificationSender/Signalr/Hubs/ProductHub.cs#L12

And hub connections using which we sendeing messages to these hubs, for example here in CreateViewModel:

• Hub creation: https://github.com/SergeyDavidovich/OMSBlazor/blob/127696762f7fa748337642dce2418b90e6a21092/src/OMSBlazor.Blazor/Pages/Order/Create/CreateViewModel.cs#L55
• Sending message: https://github.com/SergeyDavidovich/OMSBlazor/blob/127696762f7fa748337642dce2418b90e6a21092/src/OMSBlazor.Blazor/Pages/Order/Create/CreateViewModel.cs#L273