Custom translation updates (GlotPress)

[andrewlimaza]

• ENHANCEMENT: Added functionality to look for updates via our own translations server.

All Submissions:

• Have you followed the Contributing guideline?
• Does your code follow the WordPress' coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

[andrewlimaza]

One concern I have here is that Traduttore requires PHP 7.1 or higher, while this is outdated we still have sites using older PHP versions (but maybe it's okay) - https://wearerequired.github.io/traduttore/plugin-theme.html#:~:text=Note%3A%20Traduttore%20Registry%20requires%20PHP%207.1%20or%20higher.