This is the first in a sequence of patches that implement various optimizations
to transform load [copy] into load_borrow.
The optimization works by looking for a load [copy] that:
1. Only has destroy_value as consuming users. This implies that we do not need
to pass off the in memory value at +1 and that we can use a +0 value.
2. Is loading from a memory location that is never written to or only written to
after all uses of the load [copy].
and then RAUW the load [copy] with a load_borrow and convertes the destroy_value
to end_borrow.
NOTE: I also a .def file for AccessedStorage so we can do visitors over the
kinds. The reason I want to do this is to ensure that people update these
optimizations if we add new storage kinds.
