.NET 6 Upgrade and Killing of .NET Framework Support

[hughesjs]

Personally, I think it's time to leave the .NET Framework behind.

This project doesn't use anything like WinForms or WPF, so there are no issues there.

However, some of the sample projects are .NET Framework, as is the WebApi package. Which is why #32 failed rather spectacularly and I had to reset the whole thing (I had the Windows Specific Projects hidden and forgot - whoops...).

The benefits of the upgrade to .NET 6 include:

• True cross-platform support
• Access to System.Text.Json
• Will make Setup CI #53 and Setup CD #54 a lot easier if we don't have any Windows projects.

My suggested course of action would be:

• Update readme to indicate that the current version is the last which will support .NET Framework and do a major version number bump.
• Delete Hypermedia.Sample.WebApi
• Delete Hypermedia.WebApi
• Delete Hypermedia.JsonApi.WebApi
• Upgrade all .NET Standard 1.4 Libs to .NET 6
• Hypermedia.AspnetCore will probably need a rewrite the API has changed so much
• Refactor these projects to be more canonically .NET 6-like... Things like adding file-scoped namespeaces.
• Look into replacing Newtonsoft with System.Text.Json everywhere but I'd recommend waiting for Create Test Suite #42 to be completed first or there will be a nightmare regression testing it.

[ThomasBarnekow]

@hugesjs, how about client-side code that can only target netstandard2.0, for example? I am asking because I am looking for a client-side library that I ultimately use in a project that is -- very unfortunately -- tied to .NET Framework. Without going into further details, this is Microsoft's choice, not mine. I would love to be on .NET 6 etc. with all our code base.

If there is no support for netstandard2.0 at least, I would have to look elsewhere.