[clang] Introduce paged vector (PR #66430)

[Richard Smith via cfe-commits]

https://github.com/zygoloid approved this pull request.

It looks like there were a couple of unaddressed comments from my earlier reviews; I think github may have been "helpfully" hiding them from you by default. I've added comments on them so you should hopefully be able to find them.

Thanks for your perseverance, this is looking good. Only really trivial nits; for my part, I'm happy for you to go ahead and commit once you've addressed them.

https://github.com/llvm/llvm-project/pull/66430