Add windows-link crate that is raw-dylib by default and a proc-macro for formatting support

[kennykerr]

This is an idea I've been toying with for a while. While the windows-targets crate supports raw-dylib it is opt-in and will be that way for quite a while due to dependents that seem to need it. But I'd like to make it easier for most projects to adopt raw-dylib and perhaps a new crate makes sense. This crate would have a single link macro like windows-targets but it would be a proc_macro_attribute to allow rustfmt not to skip over the generated bindings.