Nightly features tracking list

[lf-]

Tracking issue for the upstream issues:

• Tracking Issue for RFC 3028: Allow "artifact dependencies" on bin, cdylib, and staticlib crates rust-lang/cargo#9096 - used by test suites as well as clipper to get clipper_inject

• fn_ptr_trait, no tracking issue >:(

  This one is quite likely fixable by adding our own trait and some clever impls since there aren't so many function pointer types we actually care about I don't think

• Tracking Issue for lazy_cell rust-lang/rust#109736 - used by clipper_inject

Please don't introduce more of these if avoidable.