Before we actually split prepared transactions and create ApplierOperation for prepared split entries, we want to first replace the exiting vector<OplogEntry*> occurrences with vector<ApplierOperation> in oplog applier where necessary. For this ticket, we can tag all ApplierOperation entries as `ApplicationInstruction::applyOplogEntry`.

The places that we want to replace are mostly writerVectors and its utilities. Notably we want to confine the use of ApplierOperation within oplog applier, and avoid changing interfaces in other places like `oplog.cpp`.