Add foreach/2 fucntion to the maps module.

Hello everyone,

I propose to add the foreach/2 function to the maps module.

The only way to iterate over maps without an accumulator is to deal with
the maps iterator manually. It's painful to write the same boilerplate
code every time to iterate over a map without an accumulator.

It's why I suggest enriching the maps module with the foreach/2
function. I've already opened a pull request[1]. I tried as much as
possible to follow the contribution guide don't hesitate if I made a
mistake somewhere.

Regards,

[1] https://github.com/erlang/otp/pull/2984

-- 
Bryan Frimin
https://www.frimin.fr
[email protected]