This is the next step towards supporting bitcode auto upgrade with opaque pointers. The ValueList now stores the Value* together with its associated type ID, which allows inspecting the original pointer element type of arbitrary values.
This is a largely mechanical change threading the type ID through various places. I've left TODOTypeID placeholders in a number of places where determining the type ID is either non-trivial or requires allocating a new type ID not present in the original bitcode. For this reason, the new type IDs are also not used for anything yet (apart from propagation). They will get used once the TODOs are resolved.