CSV files: added possibility to select PHP input file mode

[enrico69]

Description

A small modification to the CSV processor of the framework. This processeur is juste a layer
over native PHP functions. However it forces the input mode when writing into a file which is very unpleasant and lacks of flexibility.

For instance, if you want to progressively save the data in to the file, you can't: you have to save it at once. It could lead to have big amount of data stored in memory while it could be saved progressively in the file.

This small modification allows to developer to choose the input mode while not breaking the backward compatibility.

Manual testing scenarios

1. Use the Magento CSV file processor to save data in to a file, and use different input mode (w, w+...)

Contribution checklist

• [x ] Pull request has a meaningful description of its purpose
• [ x] All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[sidolov]

Please, add new method parameters according to our Backward Compatible Development Guide

[enrico69]

Done. But in my very humble opinion, it makes the code bloated. My first proposal was not breaking backward compatibility and kept the original code.

[magento-engcom-team]

Hi @sidolov, thank you for the review.
ENGCOM-1253 has been created to process this Pull Request

[magento-engcom-team]

Hi @enrico69. Thank you for your contribution.
Changes from your Pull Request will be available with the upcoming 2.3.0 release.