[clang] Introduce paged vector (PR #66430)

[Giulio Eulisse via cfe-commits]

ktf wrote:

@mikaelholmen see also https://github.com/llvm/llvm-project/pull/67958. I can't seem to create a version that avoids triggering the warning and is also compatible across both macOS and Windows. Some good idea would be appreciated, especially because I do not have a windows setup and godbolt does not seem to like LLVM as an external package.

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