Rebase of #14649 (which itself was a rebase of #11256).
Squash the two test related commits, and swapped out size usage for vsize.
Added a commit with release notes.
@conscott @meshcollider @esotericnonsense did you want to re-review here? Maybe we'll get this in before the commits hit their second birthday 🍰 .
Concept ACK 17d178f
utACK looks good to me (two years, ahh!)
utACK 17d178fb9463c195c822614eb0245188e52f8371