[ORC] Add CallViaEPC and CallSPSViaEPC utilities. (#170464)

These utilities simplify making typed async calls via
ExecutorProcessControl::callWrapperAsync.

CallViaEPC.h provides utilities for making typed async calls using a
given Serializer to serialize arguments and deserialize results.

callViaEPC takes a result handler function object (accepting
Expected<T>), an EPC reference, a Serializer, a target function address,
and arguments. The return type T is inferred from the handler's argument
type using CallableTraitsHelper.

EPCCaller wraps an ExecutorProcessControl& and Serializer, simplifying
repeated calls with the same serialization.

EPCCall wraps an EPCCaller and target function address, simplifying
repeated calls to a specific wrapper function.

CallSPSViaEPC.h provides utilities for using CallViaEPC with SPS
serialization.

SPSCallSerializer is a CallViaEPC-compatible serializer using SPS.

SPSEPCCaller takes an SPS function signature as its template argument
and applies SPS serialization to arguments and return values.

SPSEPCCall wraps an SPSCaller and a target function address, simplifying
repeated calls to a specific SPS wrapper function.