Improved error message when consuming from Uno projects with mismatched TFMs

[Arlodotexe]

Closes #185

This PR introduces a small packaging workaround that improves the error message when consuming the Toolkit from a project that needs to update the Windows version in their WinAppSDK TFM.

Originally posted in #185 (comment)

One of the possible changes to avoid error messages of this kind is to add lib/net7.0-windows10.0.18362 and lib/net8.0-windows10.0.18362 folder with a _._ file in most uno-referencing packages. This would prevent transitive dependencies to go to the wrong TargetFramework. It won't allow for the build to work, but it would not be that much misleading.