Upgrade to Blazor 0.9.0.

[david-nordvall]

First stab at upgrading to .NET Core 3.0 and Blazor 0.9.0. The major change in Blazor 0.9.0 compared to Blazor 0.7.0 is the move to Razor Components from Blazor Components (which are actually the same thing, just re-branded).

The upgrade is not complete as at least the following is missing:

• The F#-samples have not been fully upgraded (specifically the SAFE-chat sample) since I have no F# experience.
• DevToolsInterop.LogToJs() is simply disabled since the static JSRuntime class has been removed in favor of an injected IJSRuntime instance. The entire DevToolsInterop class propbably needs to be rewritten in order to handle the injected instance instead.

Other than that, everything seems to work :-).

[david-nordvall]

DevToolsInterop is now refactored and LogToJs() enabled once more.