[ET-VK] Adding batch processing in x axis to conv2d dw shader by caching input texel for reuse. (#7565)

* [ET-VK] Adding a common utility function to calculate 3d output position based on unique index.

Pull Request resolved: https://github.com/pytorch/executorch/pull/7522

This diff adds an indexing utils header file used in Vulkan backend of Executorch. The header file includes functions for converting a global index to u16 indices based on input sizes.
ghstack-source-id: 260707858
@exported-using-ghexport

Differential Revision: [D67821941](https://our.internmc.facebook.com/intern/diff/D67821941/)

* [ET-VK] Adding batch processing in x axis to conv2d dw shader by caching input texel for reuse.

Pull Request resolved: https://github.com/pytorch/executorch/pull/7526

This diff adds batch processing in the x axis to the conv2d dw shader by reusing input texel overlapping between consecutive tiles. The changes include modifying the glsl code for the conv2d dw output tile, adding a new parameter to the yaml file, and modifying the Convolution.cpp file to use the new parameter.
ghstack-source-id: 260707856

Differential Revision: [D67868671](https://our.internmc.facebook.com/intern/diff/D67868671/)

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Co-authored-by: Vivek Trivedi <5340687+trivedivivek@users.noreply.github.com>