ggml-webgpu: updated matrix-vector multiplication (#21738)
* merged properly, but slow q3_k and q5_k with u32 indexing
* Start on new mat-vec
* New format float paths working
* Working q4_0
* Work on remaining legacy q-types
* port k-quants to new matvec
* remove old shader
* Remove old constants, format
* remove accidental file
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Co-authored-by: Neha Abbas <nehaabbas@ReeseLevines-MacBook-Pro.local>
Co-authored-by: Reese Levine <reeselevine1@gmail.com>
