src: unique_ptrs in few lambdas

Few lambdas in src/node_file.cc uses conventional
pointers, turn those into unique_ptr semantics

PR-URL: https://github.com/nodejs/node/pull/23124


Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>