Add a script to check translations files

Situation

Actually, switching the language (from the GUI Settings) to "Nederlands" will print out those errors:

QString::arg: Argument missing: Tentang untuk memperbarui ke {{update_channel}} versi {{ version }}, 
QString::arg: Argument missing: Tentang untuk memperbarui ke {{update_channel}} versi {{ version }}, 
QString::arg: Argument missing: "Berkas yang Diabaikan ({{ unsynchronized_files }})" , 0

This is also the case with "Bahasa Indonesia".

Fix

Before fixing translations, we should be robust against those errors.
I propose to create a Python script that will check translations files.

The idea is:

• to retrieve possible arguments contained in every sentences from the i18n.json file (it is in english, the reference language);
• then, for each other translations files, check sentences against the reference one.

If the sentence has not the same arguments (count and name), store the error in a list:

errors.append(f"{translation_file.json} {sentence_key!r}")

At the end of all checks, if the errors list is not empty:

• prints out all errors
• exit with a failure code -1

Integration

• A new option, --check-translations, will be added to deploy scripts.
• The script will be called before tests.

Bonus

When traiting a translation file, it should be a good idea too to store excedant sentences (became obsolete at a certain point).
They will only be printed out, but not making the script to exit with a failure.