[easy] fix stack overflow in ls --json command
[easy] fix stack overflow in ls --json command

Summary: List.map was causing stack overflows with `flow ls --json .` This diff uses `rev_map` instead, which gets rid of the error.

Reviewed By: gabelevi

Differential Revision: D13088032

fbshipit-source-id: 51c84c746ac87d6d94c5b95a0d2b8abec027f96d

nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow