feat : add col2im kernels

[PABannier]

This PR implements the col2im kernel to support ggml_conv_transpose_1d on Metal. It proceeds as follows:

• Write a C kernel for col2im
• Write a Metal kernel for col2im
• Remove the old implementation of ggml_conv_transpose_1d
• Implement the one using ggml_col2im

[slaren]

When adding a new op to multiple backends, a test should be added in test-backend-ops. It should also be useful to test the implementation while working on it.