Rollup merge of #145783 - Erk-:et-cetera-span, r=compiler-errors

add span to struct pattern rest (..)

Struct pattern rest (`..`) did not retain span information compared to normal fields. This patch adds span information for it.

The motivation of this patch comes from when I implemented this PR for Clippy: rust-lang/rust-clippy#15000 (comment)

It is possible to get the span of the Et cetera in a bit roundabout way, but I thought this would be nicer.

Author: GuillaumeGomez