Wifi hal - Firmware dump permissions

we are aiming to improve logging performance by having wifi hal
directly write to the flash.

Wifi hal need to be able to create, write, and delete files in
a directory. This will be restricted to userdebug and eng builds only.

Bug: 70170285
Test: compile, run on device
Change-Id: Id0cd317411f4c393d7529aa31b501046d7350edb