Add tagging functions for Int32, Int64, Uint32, Uint64, WasmF32, WasmF64

[spotandjake]

We currently have tagging and untagging functions for the various stack allocated number types in DataStructures it would probably be beneificial if we added functions for the heap allocated ones as well. As we are not really tagging here it might make more sense to use something like loadInt32, loadInt64.
These functions currently do exist in runtime/unsafe/conv it might make sense to re-export these from DataStructures so we have a single file giving us all of our primitive conversion functions.