[CLI] add "new"/"dirty" flag on translations when source has changed

[oguimbal]

When refreshing translations from the CLI, all translation files must add a "new" flag for translations that have newly been added, or a "dirty" flag when the sentence has changed in source language.

New sentences to translate:

{
    "source": "XX",
    "new": true
}

Modified in source languages:

{
    "source": "Updated version of XXX",
    "target": "Translation of old XXX",
    "dirty": true
}