Refactored WASM rendering, added MT support for dispatcher

[kekekeks]

1. Removed previous hacks with fake platform graphics context and special cased ISkiaGpu, we are now using a proper IGlContext implementation with MakeCurrent that actually works as it supposed to.
2. Refactored canvas management in a way that can work with .NET 9 MT - canvas can be converted to OffscreenCanvas and transferred to a web worker
3. Changed render loop and dispatcher to be MT-compatible (.NET 9 MT currently doesn't support JSType.Function)

Note that the rest of the backend isn't MT-ready, so input and resize still won't work in MT mode.

[avaloniaui-bot]

You can test this PR using the following package version. 11.2.999-cibuild0048403-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[maxkatz6]

After hack-fixing previous error by also checking Environment.Version >= 9 I see this:

[Visual]Exception in render loop: 'System.DllNotFoundException: *
dotnet.native.js:1268    at Avalonia.OpenGL.GlBasicInfoInterface.Initialize(Func`2 getProcAddress) in /Users/maxkatz6/repos/Avalonia/src/Avalonia.OpenGL/DevGenerators/Generator.GetProcAddressInitializationGenerator/globalAvalonia.OpenGL.GlBasicInfoInterface.cs:line 38
dotnet.native.js:1268    at Avalonia.OpenGL.GlBasicInfoInterface..ctor(Func`2 getProcAddress) in /Users/maxkatz6/repos/Avalonia/src/Avalonia.OpenGL/GlBasicInfoInterface.cs:line 13
dotnet.native.js:1268    at Avalonia.OpenGL.GlInterface.GlContextInfo.Create(GlVersion version, Func`2 getProcAddress) in /Users/maxkatz6/repos/Avalonia/src/Avalonia.OpenGL/GlInterface.cs:line 32
dotnet.native.js:1268    at Avalonia.OpenGL.GlInterface..ctor(GlVersion version, Func`2 getProcAddress) in /Users/maxkatz6/repos/Avalonia/src/Avalonia.OpenGL/GlInterface.cs:line 48
dotnet.native.js:1268    at Avalonia.Browser.Rendering.WebGlContext..ctor(Int32 contextId, GlVersion version, Int32 sampleCount, Int32 stencilSize) in /Users/maxkatz6/repos/Avalonia/src/Browser/Avalonia.Browser/Rendering/BrowserWebGlRenderTarget.cs:line 114
dotnet.native.js:1268    at Avalonia.Browser.Rendering.BrowserWebGlRenderTarget..ctor(JSObject js, Func`1 sizeGetter) in /Users/maxkatz6/repos/Avalonia/src/Browser/Avalonia.Browser/Rendering/BrowserWebGlRenderTarget.cs:line 31
dotnet.native.js:1268    at Avalonia.Browser.Rendering.BrowserRenderTarget.GetRenderTarget(Int32 id, Func`1 sizeGetter) in /Users/maxkatz6/repos/Avalonia/src/Browser/Avalonia.Browser/Rendering/WebRenderTarget.cs:line 31
dotnet.native.js:1268    at Avalonia.Browser.Rendering.RenderTargetBrowserSurface.BrowserPlatformGraphics.get_Target() in /Users/maxkatz6/repos/Avalonia/src/Browser/Avalonia.Browser/Rendering/RenderTargetBrowserSurface.cs:line 63
dotnet.native.js:1268    at Avalonia.Browser.Rendering.RenderTargetBrowserSurface.BrowserPlatformGraphics.get_IsReady() in /Users/maxkatz6/repos/Avalonia/src/Browser/Avalonia.Browser/Rendering/RenderTargetBrowserSurface.cs:line 65
dotnet.native.js:1268    at Avalonia.Rendering.PlatformRenderInterfaceContextManager.get_IsReady() in /Users/maxkatz6/repos/Avalonia/src/Avalonia.Base/Rendering/PlatformRenderInterfaceContextManager.cs:line 25
dotnet.native.js:1268    at Avalonia.Rendering.Composition.Server.ServerCompositor.RenderCore(Boolean catchExceptions) in /Users/maxkatz6/repos/Avalonia/src/Avalonia.Base/Rendering/Composition/Server/ServerCompositor.cs:line 221
dotnet.native.js:1268    at Avalonia.Rendering.Composition.Server.ServerCompositor.RenderReentrancySafe(Boolean catchExceptions) in /Users/maxkatz6/repos/Avalonia/src/Avalonia.Base/Rendering/Composition/Server/ServerCompositor.cs:line 194
dotnet.native.js:1268    at Avalonia.Rendering.Composition.Server.ServerCompositor.Render(Boolean catchExceptions) in /Users/maxkatz6/repos/Avalonia/src/Avalonia.Base/Rendering/Composition/Server/ServerCompositor.cs:line 174
dotnet.native.js:1268    at Avalonia.Rendering.Composition.Server.ServerCompositor.Render() in /Users/maxkatz6/repos/Avalonia/src/Avalonia.Base/Rendering/Composition/Server/ServerCompositor.cs:line 163
dotnet.native.js:1268    at Avalonia.Rendering.RenderLoop.TimerTick(TimeSpan time) in /Users/maxkatz6/repos/Avalonia/src/Avalonia.Base/Rendering/RenderLoop.cs:line 111' (RenderLoop #660812652)

Note sure what to do here. That's running on .NET 8 SDK without threading.

[avaloniaui-bot]

You can test this PR using the following package version. 11.2.999-cibuild0048435-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[avaloniaui-bot]

You can test this PR using the following package version. 11.2.999-cibuild0048443-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]