Tries to add files to .NET Core projects

[JesseNewman19]

.NET Core projects do not need to "include" files by default--they only exclude.

I think there should be proper support for detecting when the csproj file is a .NET Core project and properly disable the "File is not found in project" popups for those files.

[alexjamesbrown]

I also found this issue today

[szyb]

The workaround I used is to add to settings:
"csproj.excludeRegex": "ProjectName"

[BinToss]

Checking the <Project> element for Sdk="Microsoft.NET.Sdk" should suffice.
SDK-style projects use implicit File Includes regardless of the TargetFramework in both DotNet/VSCode and VS IDE.

Projects that use the .NET Framework (.NET 4.x) format lack the Sdk property and require explicit includes.