Partially fixes rust-lang#10413. This only handles lifetimes, as they're much
more "obvious" than the type parameter list would be, as that implies
that we probably want to mirror `ast::Generics` as well as all of the
individual pieces. That should probably have an RFC.

These are essentially just treated the same as idents. They're a single
token, and are quite pervasive, so we interpolate them back into a real
token rather than handling `NtLifetime` all over the parser.

This change is specifically needed in Diesel in order for us to provide
a "normal macro" alternative to some of our syntax extensions. With this
change, we'd be able to have a decent stable story without syntex.

All of the other non-terminals have this implementation. If we allow
them in macros, we should allow them in quoting