This reverts 4d10c1165442cbbbc0017b48fcdd7dae1ccf3678 and its two
dependent commits: e6b9805b574bb5c90263ec7fbcb94df76d2807a4 and
c243406a695ca056a07ef4064b0f9feee7685320, see discussion in
https://github.com/llvm/llvm-project/pull/165598#issuecomment-3563825509.

This adds support for calling virtual destructors.

This adds support for dynamic cast handling and generating
`cir.dyn_cast` operations and `cir.dyn_cast_info` attributes.

This does not include support for lowering the dynamic cast to LLVM IR,
which will require changes to the LoweringPrepare pass that will be made
in a future change.

This also does not yet handle dynamic cast to void or exact dynamic
casts.

Upstream the RTTI builder with helpers and used them in the VTable
Definitions

Issue https://github.com/llvm/llvm-project/issues/154992

This adds the support for implicit VTT arguments in constructors.

This adds support for emitting virtual table tables (VTTs) and
construction vtables.

This change adds support for emitting multiple tables in a global vtable
object to handle the case of multiple-inheritence.

This adds a simplified version of the code to emit vtables. It does not
yet handle RTTI or cases that require multiple vtables.

This adds support for initializing the vptr member of a dynamic class in
the constructor of that class.

This does not include support for lowering the
`cir.vtable.address_point` operation to the LLVM dialect. That handling
will be added in a follow-up patch.