[DataLayout] Refactor storage of non-integral address spaces
Instead of storing this as a separate array of non-integral pointers,
add it to the PointerSpec class instead. This will allow for future
simplifications such as splitting the non-integral property into
multiple distinct ones: relocatable (i.e. non-stable representation) and
non-integral representation (i.e. pointers with metadata).
Reviewed By: arsenm
Pull Request: https://github.com/llvm/llvm-project/pull/105734