Add support for adding global dependencies to all incremental targets

Add support for adding global dependencies to all incremental targets.
Say I have a file that defines all the external resources/packages my project is using and that is updated with the repo, I'd like to force full build if that files changes.

For example to have something like:
``

If MyProject.config changes, I expect all incremental projects from my repo to be-rebuilt (ie: vcxproj, csproj, everything that executes the Build target).

Start by tracing the Build target and incremental-target handling, then compare dependency declarations in vcxproj and csproj projects. Done means a MyProject.config-style input can be declared once and causes every incremental project executing Build to rebuild when it changes.

Written by the indexing model from the issue text.