[ORC] Move EPC load-dylib and lookup operations into their own class.
This keeps common operations together, and should make it easier to write
re-usable dylib managers in the future (e.g. a DylibManager that uses
the EPC's remote-execution APIs to implement load and lookup).
llvm-project
db21bd4f - [ORC] Move EPC load-dylib and lookup operations into their own class.
