Replace Newtonsoft.Json package with System.Text.Json

[Bertk]

• uses System.Text.Json instead of Newtonsoft.Json for nuget packages
• integration test is still using Newtonsoft.Json
• generates code coverage report #1516 (Azure DevOps build pipeline)

:exclamation: PR #1510 should be merged before this one. The System.Text.Json updates shall be merges separately.

[Bertk]

@daveMueller @MarcoRossignoli This PR replaces Newtonsoft.Json from coverlet.core with System.Text.Json and removes many assemblies from the nuget packages. Please share your thoughts on this.

[MarcoRossignoli]

That's really cool, @daveMueller do you plan to review this one?

[daveMueller]

Yes I will. As I understood it's the same changes as in #1510 but instead of updating Newtonsoft.Jsonit uses System.Text.Json.

[Bertk]

I will rebase this branch after #1510 is merged :wink:

[MarcoRossignoli]

@Bertk I see you a lot active on coverlet, let me know if you're interested to become a co-maintainer and help to keep the product in a good shape.

You can contact me on twitter https://twitter.com/MarcoRossignoli or let me know how we can have a chat

Not mandatory at all it's OSS so no obligation.

cc: @daveMueller @petli @tonerdo

[Bertk]

@MarcoRossignoli Can we have a chat on Monday Zoom or MS Teams will be fine.

[Bertk]

@daveMueller @MarcoRossignoli Please review and approve PR.

Please note: I wanted to check stderr with the last commit but after the update the CI tests were successful.

By the way, the obsolete PR #1358 should be closed.

[Bertk]

@daveMueller Please review PR. This has also the code coverage report for the AzureDevOps build pipeline.

[Bertk]

@daveMueller I added code coverage badge and trx files which have the output attachments. The PR is ready for merge.