i18n: Allow selecting a different language than device setting

[chrisbobbe]

Currently, the app UI follows the device setting for what language it should try to display in.

This issue is for an in-app setting to choose any language we have translations for, instead of always following the device.

An instance of:

• Store some client settings #97.

[Gaurav-Kushwaha-1225]

Hi @chrisbobbe,

This storing of some client settings isn't yet implemented for Theme Switching among dark/light/system.
Am I right?

If yes. Then, where we might add this feature for language now and theme later on.
I would suggest keeping it here, in the menu button.

Thank you.

[chrisbobbe]

Hi @Gaurav-Kushwaha-1225, welcome! Storing some client settings is #97, and I see a core team member (@PIG208) has just self-assigned that issue. So let's wait to work on this until he implements a settings UI where this setting will go. For now, if you'd like to contribute, please choose a different issue to work on.

[gnprice]

As an example of where this is desired, we heard from a user today:

In our team we use English as a default language in communication and collaborative apps, tho our native language is not English. Right now in Flutter app I can't change system language, but in legacy app it's not a problem.
[…] my system language is not English

So they want Zulip in English although they have a different language chosen for the system overall.

[AshutoshKhadse23]

Hello @chrisbobbe ,
Can you assign this to me?

issue.1139.mp4

[gnprice]

Thanks. Instead of a popup submenu, let's put this as a screen underneath the main settings screen — that's a UX that will scale better when there are dozens of translations, which I expect there to be soon after the Zulip project as a whole completes our migration to Weblate and asks our community of translation contributors to translate this app there.

For a model of how that UI can work, see the language setting in the legacy app.

To make it available from the choose-account screen, we can add an option to go to the settings screen as one of the options in that menu.

[AshutoshKhadse23]

Hello @gnprice ,
Created PR based upon the updates required in UX