Create sync and async sample for using Utf8JsonReader.

[ahsonkhan]

Summary

Utf8JsonReader sample showcasing how to use the APIs to accompany the .NET Core 3.0 preview 1 release.

• Includes a synchronous sample where JSON data is read from a file (~2 MB).
• Includes an asynchronous sample where JSON data is read from the web.

Borrowed the data from: https://github.com/Hipo/university-domains-list (MIT License)

E:\GitHub\Fork\samples\snippets\csharp\how-to\json> dotnet run -c Release
Expected output:

Reading JSON from file, sync: 827 out of 9674 universities worldwide have names starting with 'University of' (i.e. 8.55%)!
Reading JSON from web, async: 209 out of 2157 American universities have names starting with 'University of' (i.e. 9.69%)!
Reading JSON from web, async: 827 out of 9674 universities worldwide have names starting with 'University of' (i.e. 8.55%)!

cc @richlander, @glennc, @terrajobst, @stephentoub

[BillWagner]

Overall, this is great.

I had one small suggestion, and then once you've address Stephen's comment, we'll merge.

[ahsonkhan]

This is ready to merge.

[richlander]

I think this sample should be in core directory. Why in the csharp directory?

[BillWagner]

@ahsonkhan @richlander

Other than the folder location, this is ready to go. It likely fits better under core than under C# because the concepts it explains are more about the library than about the language.

Is there an article that will accompany this sample? Where will that go? We try to mirror the sample folder structure with the docs folder structure. That can help us find the right location.

[ahsonkhan]

I think this sample should be in core directory.

Other than the folder location, this is ready to go.

Done. Moved to a new "whats new in 30" folder.

[richlander]

Sorry to be so picky and for not being specific ... I was expecting something more like ~/core/json

[ahsonkhan]

Sorry to be so picky and for not being specific ... I was expecting something more like ~/core/json

That's easy enough to fix :)