docs: Format efl_file.h
Summary:
And polish a bit.
Ref T7717
Test Plan: Only docs updated
Reviewers: zmike
Reviewed By: zmike
Subscribers: bu5hm4n, cedric, reviewers, committers
Tags: efl
Maniphest Tasks: T7717
Differential Revision: https://phab.enlightenment.org/D8498