[clang] Introduce paged vector (PR #66430)

[Vladimir Vereschaka via cfe-commits]

vvereschaka wrote:

@vgvassilev ,
got failed tests: https://lab.llvm.org/buildbot/#/builders/86/builds/66095

* LLVM-Unit :: ADT/./ADTTests.exe/PagedVectorTest/EmptyTest
* LLVM-Unit :: ADT/./ADTTests.exe/PagedVectorTest/HalfPageFillingTest
* LLVM-Unit :: ADT/./ADTTests.exe/PagedVectorTest/ShrinkTest

would you take care of it?

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