Fix T87991.
To inset a face in Orthographic view variable, `amount` returns negative value for present logic.
To improve inset function for such small case, following changes were made.
variable `is_not_front` used to check using pixel value if selected face is facing towards screen.
If bool value is true, set initial length `0`.
Logic with pixel value may not be the accurate way.
>Note: Patch is not ready for review, some improvements required here.