[ORC] Change SPSExecutorAddr serialization, SupportFunctionCall struct.

SPSExecutorAddr will now be serializable to/from ExecutorAddr, rather than
uint64_t. This improves type safety when working with serialized addresses.

Also updates the SupportFunctionCall to use an ExecutorAddrRange (rather than
a separate ExecutorAddr addr and uint64_t size field), and updates the
tpctypes::*Write data structures to use ExecutorAddr rather than
JITTargetAddress.