ggml : replace conv 1D - 2D stage_0 and stage_1 with im2col and mul_mat (#564)

ggml : replace conv 1D - 2D stage_0 and stage_1 with im2col and mul_mat (#564)

* added conv2d stage 0 - 1 cuda kernels

* add im2col + refactor conv1d and conv2d

* fix params invalid index

* add conv1d and conv2d unit tests

* resolving wrong values and fix mul_mat validation

* improve tests + reduce code duplication

* add cuda kernels

* more data test

* fix ggml_op_count to 70

* add temp test - gemm != mul_mat

* tests : fix test-mul-mat matrix multiplication

* test-mul-mat match gemm == ggml_mul_mat with conv2d op

* replaced gemm by ggml_mul_mat

* ggml_mul_mat cpu backend support fp16 src1

* ggml_mul_mat cuda backend fp16 fixed

* remove unnecessary ggml_cont and removed conv1d-2d functions deprecated

* some fixes

* explain conv1d reshapes

* ggml : fix tests on Arm + do not use BLAS for F16 data

* tests : fix FP16 handling on Arm

* ggml : avoid ggml_cont and ggml_transpose in ggml_conv_xd

* ci : switch back to release

* cuda : fix wrong pointer usage

* ggml : add metal support for im2col and f16xf16 mul mat

* ggml : im2col opts

* Update src/ggml-cuda.cu

Co-authored-by: slaren <redacted>
---------

Co-authored-by: Georgi Gerganov <redacted>
Co-authored-by: slaren <redacted>