* Organize and collect metal subroutine templates and elements in `metal/kernels/steel/`
* Update gemm elements for better performance
* Add split-K specialization for gemm
* Add `addmm` primitive, op and bindings for fused matmul and bias addition
* Update tests and benchmarks as needed
* Allow arbitrary first dim on qmm_t and qmv
* Allow arbitrary first dim on qmm and qvm
* Specialized aligned vs unaligned case
* Add more checks for valid quantizations
* added leaky_relu relu6 softplus elu celu logsigmoid
* minor fixes for docstring and benchmark imports
* fixed elu implementation and added tests
* added tests for optional param, changed leaky_relu param to fit pytorch documentation