Add User Input Abstraction and WebRTC Datachannel Implementation

[Hong-Xiang]

Pushing user pointer events from browser to server, with x, y normalized to target element. Design how to integrate it with pull based render loop system

[Hong-Xiang]

After long investigation and trying both Blazor server interactive and Blazor WASM, optionally combined with SignalR, it truns out that:

• Its possible to use purely message passing based approach to build connection, message passing means purely fire and forget style (no request-response support), since signal server for RTCPeerConnection can be implemented over three simple bidirectional channel
• Using Blazor (server interactive or wasm) make implementation significantly more complex due to
  • interop of C# and JS is still complex, especially when considering about passing/disposing JSObjectReference
  • Blazor model will change DOM elements, which added complexity on boundary of Blazor managed DOM elements and our own logic controlled elements

As a result, we change our design to use purely static MVC model in ASP NET Core (which actually bring more support to write dynamic values into html template), and implement connection related logic directly in JS.

[Hong-Xiang]

closed by #20