add google magika inference example (ggml/748)

* add magika inference example

* ggml : fix unaligned accesses in custom ops

* ggml : fix FP32 GELU for values that exceed the FP16 range

* use ggml_pool_1d

* add README

* Update README.md

* pad inputs if the files are too small

* cleanup

ggml-ci