[llvm] Introduce paged vector (PR #66430)

[Giulio Eulisse via llvm-commits]

ktf wrote:

> @ktf could you take a look at this?

Sure, I did https://github.com/llvm/llvm-project/pull/67972 with your suggestion, however I am not sure how I can run the benchmark myself.

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