Moving a project fails if the project imports msbuild files other than paket.restore.targets

[ModernRonin]

Say the csproj contains something like

<Import Project="..\..\package.props" />

When the project is moved (not just renamed), then this relative path needs adjusting. This isn't currently happening, so the move fails, albeit safely (no changes).

Seeing as we already adjust such paths for imports of paket, it should be fairly simple to extend that code to cover all <Import Project...> directives.