Allow progress report

[ldwedari]

Allow to provide a callback that is called after a chunk us completed or trigger a progress event.
The best place to call this is at the end of the coreCall method.

[szydan]

Hi
If anyone is still looking for an implementation which supports progress report
Here is my library called chunksha - the core was borrowed from rusha and I've added progress reporting and support for large files
https://szydan.github.io/chunksha/