Add Uno Todo Sample App

[trydalch]

This is close to functional, but there's problems refreshing.

I started up the WinUI sample and my Uno sample and then pointed them to the sample server running locally.

On startup, both applications would get the list of todos with the correct versions. But as I made changes, some changes would sync but others wouldn't.

It seems to be an issue on the client side, because when I used swagger to check what the server returned, it was correct.

What could be the issue? Could you take a look?

There's this issue, some cleanup and the behaviors need to be added, but then the sample should be ready.

[trydalch]

This would close #83

[adrianhall]

I take it you want to wait until refresh is working before converting to a real PR?

[trydalch]

Yes, but though I've stared at it I'm not sure why the refresh isn't working properly and was hoping perhaps someone who knows the tool better could take a look.

[trydalch]

It looks like it's a bug in the WinUI sample. The data is correct, but the VisualState of the checkbox does not always match the IsComplete property.

[trydalch]

You'll notice I added a TodoItemViewModel to both the Uno sample and WinUI sample. This was to fix the UI binding issue where the UI wouldn't get PropertyChanged events when the data was edited on another client and then refreshed. Perhaps there was a more simple solution, but this works.

[trydalch]

PR is cleaned up and only includes changes related to the Uno sample. Ready for another review.

[adrianhall]

TODO:

• Remove the change to ObservableConcurrentCollection - it's incorporated into the latest client code.
• Remove identifying information from ApplicationPublisher in csproj
• Minimize the number of lements in UnoFeatures to only those required by the app
• Replace Endpoint with https://YOURSITE.azurewebsites.net/ (same as all the other samples)
• Update NuGet packages to non-vulnerable versions

Bugs:

• On running (with the service integrated), I get COMException in line 31 of TodoListPge

[adrianhall]

See TODO list in comments.