[ORC] Replace ExecutorSymbolDef with ExecutorAddr in remote lookup. (#201492)
Update DylibManager and associated interfaces to return ExecutorAddrs
for remote symbols, rather than ExecutorSymbolDefs. No clients were
using the flags component of ExecutorSymbolDef, and this brings the
SimpleExecutorDylibManager implementation in OrcTargetProcess into
closer alignment with the NativeDylibManager implementation in the new
ORC runtime.