ggml : improve ADD_REL_POS perf in SAM by doing it inplace + broadcast BLAS mul_mat...

ggml : improve ADD_REL_POS perf in SAM by doing it inplace + broadcast BLAS mul_mat (#466)

* Improve ADD_REL_POS perf in SAM by doing it inplace

- Add unit tests for the ADD_REL_POS operation
- I am not sure if this is valid implementation as we reuse the src0
  memory in order to avoid copying it
- When running SAM with the "Example output" command, image, point and
  16 threads, this reduces the cumulative time of the ADD_REL_POS operation
  from 1000-1100 ms to 180-200ms
- There is further room for optimization in the access patterns used in
  the implementation of the opration

* Add non-inplace version for the GGML_OP_ADD_REL_POS

* Fix map_unary warnings and refactor LayerNorm2d + remove ggml_cont in it

* Fix Mac printf format warnings

* sam : add ggml_graph_print() comment

* ggml : add broadcast support for BLAS ggml_mul_mat() (#460)

* Remove not needed build_forward_expand from add-rel-pos unit test

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Co-authored-by: Georgi Gerganov <redacted>