.NET 7 (Preview 6) changes and additions

[jaffinito]

Description

Adds .NET 7 apps and build targets for our various integration tests.

This is currently targetting Preview 6

Author Checklist

• [ ] Unit tests, Integration tests, and Unbounded tests completed
• [ ] Performance testing completed with satisfactory results (if required)
• [ ] Agent Changelog or Lambda Agent changelog updated

Reviewer Checklist

• [ ] Perform code review
• [ ] Pull request was adequately tested (new/existing tests, performance tests)
• [ ] Review Changelog

[github-actions[bot]]

This PR has been marked stale after 30 days with no activity. It will be closed in 5 days if there is no activity.

[nr-ahemsath]

We are keeping this draft PR open as we continue to work on making sure that we will support .NET 7 when it goes GA.

[nr-ahemsath]

Looks pretty good! I think to merge this we need to add some steps to the all solutions build to install the .NET 7 SDK in the build/test steps.

I made the change to install the .NET 7 preview SDK, but it looks like the version of Visual Studio installed in the windows-2022 runner (17.3.something) won't pick it up. This jives with how I had to install Visual Studio 17.4.1 Preview in order to use the .NET 7 Preview 7 SDK on my local system. I did search for how to install a preview version of Visual Studio in a GHA runner but didn't find anything.

To jog my memory, I looked at what was done last year for .NET 6, and found this PR: https://github.com/newrelic/newrelic-dotnet-agent/pull/790/files. What's notable is that that PR was merged on 11/4/21, whereas the official GA date for .NET 6 was 11/8/21. So, it may be that once we get to release candidates for .NET 7, a newer version of Visual Studio and MSBuild will be available and things will start working.

[nr-ahemsath]

Since we merged the other .NET 7 branch, which was initially branched off of this one, this can be closed.