Rollup merge of #141249 - fee1-dead-contrib:push-mwxxsvrsotvs, r=oli-obk

introduce common macro for `MutVisitor` and `Visitor` to dedup code

helps with #127615.

I can do everything in one go but I figured it might be worth it to open a PR first for vibeck.

r? oli-obk

Author: matthiaskrgr