vulkan : added the PAD_REFLECT_1D operation (#26586)

* vulkan : added PAD_REFLECT_1D operation

Implemented the GGML_OP_PAD_REFLECT_1D operation for the Vulkan backend

Changes:
- pad_reflect_1d.comp: implemented the GLSL compute shader with reflection logic
- vulkan-shaders-gen.cpp: register the shader for SPIR-V compilation
- ggml-vulkan.cpp: pushed constants struct, pipeline creation,
  supports_op, dispatch function, compute switch and debug validation

Tested the PAD_REFLECT_1D on Intel Iris Xe (Vulkan 1.4, Mesa 25.2.8):

Correctness:
  PAD_REFLECT_1D(type=f32,ne_a=[512,34,2,1],pad_0=10,pad_1=9) = Pass
  PAD_REFLECT_1D(type=f32,ne_a=[3000,384,4,1],pad_0=10,pad_1=9) = Pass
  2/2 tests passed
 - All test are passed

Performance:
  ne_a=[512,34,2,1] -> 5.38 us/run, 24.55 GB/s
  ne_a=[3000,80,1,1] -> 30.09 us/run, 59.62 GB/s
  ne_a=[3000,384,4,1] -> 158.31 us/run, 54.39 GB/s

* Update ggml/src/ggml-vulkan/vulkan-shaders/pad_reflect_1d.comp

Co-authored-by: Jeff Bolz <jbolz@nvidia.com>

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Co-authored-by: Jeff Bolz <jbolz@nvidia.com>