Update on "[ET-VK] Replace Uniform buffers with push constants for copy op"

This diff replaces uniform buffers with push constants for copy op in the Vulkan backend of Executorch. The changes include updating the GLSL code to use push constants instead of uniform buffers and updating the C++ code to pass the sizes as push constants to the shader.

Differential Revision: [D66890851](https://our.internmc.facebook.com/intern/diff/D66890851/)

[ghstack-poisoned]

Author: trivedivivek