[clang] [RFC] Initial implementation of P2719 (PR #113510)

[Oliver Hunt via cfe-commits]

ojhunt wrote:

These updates in principle bring the major semantics up to match P2719r4

Primary changes:
* CV qualifiers are dropped
* size and alignment parameters become mandatory, semantics for placement cleanup are updated to permit this, and to permit cleanup when the cleanup operator delete "matches" a usual deallocation function
* the allocation and cleanup delete operators must be either both type aware or neither type aware

To do:
* A class that defines a type aware new or delete must define a complementary type aware operator


https://github.com/llvm/llvm-project/pull/113510