Directory.Build.props and Directory.Build.targets are handled by the
project system, so are not included in this change.

* Add binding redirects for System.ValueTuple and System.Xml.ReaderWriter
* Also add binding redirects for InteractiveHost

Ensure that all *.*proj, *.props, and *.targets files are prefixed with the xml and copyright elements

These are built with the core framework key, not the key Roslyn uses.

This removes the hard-coded binding redirects that exist within our
source tree in favor of redirects that are computed automatically. This
takes advantage of the built-in binding redirect generation support
in MSBuild. In order to get the redirects to merge properly with
the static stuff we have, I renamed the .exe.config files to App.config
which is the name the tooling looks for.

Addresses #7612.