Rollup merge of #145018 - AlexanderPortland:rustc-public-hash, r=scottmcm

Derive `Hash` for rustc_public types

This derives `Hash` for the rustc_public versions of `Rvalue`, `Place`, `Span`, and all the types they contain. As far as I can tell, the internal versions of all these types already implement `Hash`, so it would be helpful if the public versions implemented it too!

Author: tgross35