test(draft): combined WebGL + Mono 3D compatibility validation (#294 + #296) - #300

'TestServer.TestServer(IWebHostBuilder)' is obsolete: 'IWebHost, which this method uses, is obsolete. Use one of the ctors that takes an IServiceProvider instead. For more information, visit https://aka.ms/aspnet/deprecate/008.' (https://aka.ms/aspnet/deprecate/008)

'WebHostBuilder' is obsolete: 'WebHostBuilder is deprecated in favor of HostBuilder and WebApplicationBuilder. For more information, visit https://aka.ms/aspnet/deprecate/004.' (https://aka.ms/aspnet/deprecate/004)

'Scintilla.CaretLineVisible' is obsolete: 'Use CaretLineBackColor with alpha channel instead.'

Non-nullable field '_tslCompiler' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the field as nullable.

The field 'ToolStripRadioButtonMenuItem.mouseHoverState' is assigned but its value is never used

The field 'ToolStripRadioButtonMenuItem.mouseDownState' is assigned but its value is never used

Possible null reference return.

Possible null reference return.

Possible null reference return.