Migrate to .NET 6.0

[TimLariviere]

Now that I resolved both the issue with resources on Android, and created templates for F# / NET 6.0 on mobile, we can migrate Fabulous to .NET 6.0 :)

Tasks:

• [x] Fabulous
• [x] Fabulous.XamarinForms
• [x] CounterApp
• [x] TicTacToe
• [x] FabulousWeather
• [x] FabulousContacts
• [x] Templates

I had to disable PancakeView in FabulousWeather and XF.Maps in FabulousContacts because it's not compatible with .NET 6.0

[TimLariviere]

IDE support is lacking for the moment.

If you want to run the samples, you'll need:

• Create a personal access token for your GitHub account
• Change USERNAME and TOKEN in nuget.config file with your GitHub account name and your generated token
• Have dotnet v6.0.101 installed
• Have workloads installed

  dotnet workload install ios android

• For iOS:

  dotnet run --project samples/Xamarin.Forms/CounterApp/iOS/CounterApp.iOS.fsproj

• For Android:

  
  // run this command a 2nd time if it failed with a message about "Resource" not being found
  // you'll also need an attached device/emulator

dotnet run --project samples/Xamarin.Forms/CounterApp/Android/CounterApp.Android.fsproj