Rollup merge of #137723 - onur-ozkan:cfg-ver-description, r=pietroalbini,weihanglo

Make `rust.description` more general-purpose and pass `CFG_VER_DESCRIPTION`

Moves the `description` field from the `rust` section to the `build` section as it can be useful for tools and is not specific to rustc. Also passes this value to tool builds through the `CFG_VER_DESCRIPTION` env.

Motivated from https://rust-lang.zulipchat.com/#narrow/channel/326414-t-infra.2Fbootstrap/topic/Propagate.20rust.2Edescription.20to.20tools.20in.20dist.20build

Author: jieyouxu