[V17] [V18] Arabic encoding issue in the PO file

[Atteqany]

Why this issue?
It seems a file transfer problems where the Arabic characters weren't preserved properly or text editor issues that don't properly support right-to-left (RTL) languages and UTF-8 encoding. Is it by one of the contributors while editing ?

What is the issue?
All Arabic texts in the PO files (for ex. account_financial_report/i18n/ar.po) have been corrupted and appear as such symbol ?????????????? ???????

Affected Version?
V 17 - V 18

NOW, there is no translation.

[CoralieSantos]

I am working on a V17 odoo and I have the same issue in French. To correct it, I have loaded a new .po file on Odoo but it's OK only on Odoo and not when I export a report in Excel.
On my base in local, I added the line "# -- coding: utf-8 --" on the top of the files open_items_wizard.py, open_items_xlsx.py and abstract_report_xlsx.py and replace ?? by the correct characters and it seems to be working. It seems to be working also if I only add the line "# -- coding: utf-8 --" on the top of the file abstract_report_xlsx.py.
Sorry, I am new on Odoo OCA and I didn't want to make mistakes while trying to fix a part, so I didn't correct it directly. Hoping that my comment can help