Rollup merge of #121648 - jieyouxu:from-into-raw-parts-docs, r=Nilstrieb

Update Vec and String `{from,into}_raw_parts`-family docs

- Fix documentation argument order to match the code argument order for consistency.
- Add return argument description for `{Vec,String}::into_raw_parts` to match their `from*` counterparts.

Author: matthiaskrgr