Since we are modifying the NuGet targets file, can we do a few things here:

- Add a huge XML comment block at the top of the file indicating why and what has changed, and reminding people to be careful not to overwrite the file with any other changes without carefully reviewing the diffs
- Consider adding a Message with high importance added in the RestorePackages target here to effectively explain as much; i.e. `Patched NuGet RestorePackages target in use to enable building without access to private NuGet feeds.`