This makes it easier to understand conceptually why a ValueOwnershipKind with
Any ownership is invalid and also allowed me to explicitly document the lattice
that relates ownership constraints/value ownership kinds.
Today unchecked_bitwise_cast returns a value with ObjCUnowned ownership. This is
important to do since the instruction can truncate memory meaning we want to
treat it as a new object that must be copied before use.
This means that in OSSA we do not have a purely ossa forwarding unchecked
layout-compatible assuming cast. This role is filled by unchecked_value_cast.
As part of bringing up ossa on the rest of the optimizer, I am going to be first
moving ossa back for the stdlib module since the stdlib module does not have any
sil based dependencies. To do so, I am adding this pass that I can place at the
beginning of the pipeline (where NonTransparentFunctionOwnershipModelEliminator
runs today) and then move NonTransparentFunctionOwnershipModelEliminator down as
I update passes. If we are processing the stdlib, the ome doesn't run early and
instead runs late. If we are not processing the stdlib, we perform first an OME
run early and then perform an additional OME run that does nothing since
lowering ownership is an idempotent operation.
