[Refactor] Move export related functions into the `export()` function

Context

All the examples provided within the export use the same sequence of functions between the (optional) quantization step and the scheduler_export() function.
Currently these functions are split between the example script (fuse_to_metaops, set_datatype, ...) and the export() function (adapt_to_backend, set_dataformat, ...).

Changes

This MR aims to bring all the export related functions into the export() function, cleaning the example export scripts and simplifying maintainability.

It is now possible to pass the aidge_cmp and save_outputs compilation options as arguments to the Makefile.

👾 Bug fix : The SAVE_OUTPUTS option was actually including <sys/types.h> at the begining of the forward.cpp. Removing the corresponding lines caused a series of bugs, as some kernels now use size_t contained in this library. This MR now includes <sys/types.h> on top of each kernels which needs this library instead of including it in the forward.cpp generated file.