Update base for Update on "[ET-VK] Storing positions in uint16 to instead of int in conv2d pw shader."

This diff modifies the `conv2d_pw_s1p0.glsl` shader to store positions in `uint16` instead of `int`. The changes include adding the necessary extension for explicit arithmetic types, updating the type definitions for `TILE_SIZE_X` and `TILE_SIZE_Y`, and changing the type of the `pos` array.

Differential Revision: [D75423935](https://our.internmc.facebook.com/intern/diff/D75423935/)

[ghstack-poisoned]

Author: trivedivivek