Updated WinUI package to min 17763, update WinAppSdk to 1.1.4

[Arlodotexe]

This PR changes the TargetFramework for the WinUI package to net5.0-windows10.0.17763.0, the minimum LTS version supported by the WinAppSDK.

It also updates the Microsoft.WindowsAppSDK package to 1.1.4.

[michael-hawker]

@Arlodotexe forgot you mentioned you were making this PR, I also made some updates in #20 as some general clean-up. I think you missed a couple of other spots.

We can pull that out of mine and into yours though. As it also seems there may be some general build clean-up we need to do.

[michael-hawker]

Even on the main build we're failing, so there's some other tweak we need:

Build FAILED.

       "D:\a\1\s\ColorCode.sln" (Pack target) (1) ->
       "D:\a\1\s\ColorCode.WinUI\ColorCode.WinUI.csproj" (Pack target) (4) ->
       (ResolveRuntimePackAssets target) -> 
         C:\hostedtoolcache\windows\dotnet\sdk\5.0.403\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.FrameworkReferenceResolution.targets(415,5): error NETSDK1112: The runtime pack for Microsoft.Windows.SDK.NET.Ref was not downloaded. Try running a NuGet restore with the RuntimeIdentifier 'any'. [D:\a\1\s\ColorCode.WinUI\ColorCode.WinUI.csproj]

    0 Warning(s)
    1 Error(s)

@Arlodotexe want to pull in commits c4fec71 953d509 4ab07cd a48d4cd (all but the license change from my other PR) here, and then see what happens when you run the build.bat locally? And see what else we need to tweak?

[michael-hawker]

Moved to #26, going to close this one.