Support Directory.Build.targets

[sorensenmatias]

If two projects are sharing PackageReferences using a Directory.Build.targets file, Snitch is reporting the shared PackageReferences as removable from both projects.
See here for more information: https://docs.microsoft.com/en-us/visualstudio/msbuild/customize-your-build?view=vs-2022

[felpel]

The tool doesn't work so well with Directory.Build.props neither, with many false positives.

[patriksvensson]

It's a complex problem to solve since a design-time build doesn't provide information (to my knowledge) about the origin of the package/project reference. I can take a look when I have time, but I can't promise it's solvable. If anyone wants to take a stab at this, feel free to do so!