[ENH][MOD] Migrate doc/devtools/commit_translations_by_lang.php to Git instead of SVN

This script was committing translations directly to svn/trunk so as we don't want anymore to write directly to svn I have migrated the script to use Git instead.

For more information please visit this task (if you have access): https://avan.tech/item43591-doc-devtools-export_all_translation_to_file-php-should-be-moved-to-Git