Refacto language + add navigator preferences

[louisgreiner]

Description

• Initialize application language with navigator language if no preference (= first connection) in localStorage
• Allow to change language from the application without window reload
• Allow to change language from the outer of the application with @Input (setter) (in standalone mode especially)

Issues

• I renamed "locale" -> "language" since a locale is something like "fr-FR" and a language "fr", and we use "fr" as value for the language ; but i can revert these changes and bring back the "locale"
• Cannot use @Input (getter) to uniformize the code, because the getter is called at any change (including mouse move), then involving too many actions and crash the application
• (Edit: removed) Could we also remove this button ? @aiAdrian or is it still used for demo purpose on your side ?
  

Checklist

• This PR contains a description of the changes I'm making
• I've read the Contribution Guidelines
• I've added tests for changes or features I've introduced
• I documented any high-level concepts I'm introducing in documentation/
• CI is currently green and this is ready for review

[aiAdrian]

Looks good!

Remove :

Removing the switch would be fine for standalone application. Up to you - if there remove ends in a benefit then just remove it. Otherwise fine from ourside

Don't remove :

This language switch should stay there because the user might want to switch manually the language preference - especially he works for a company with fixed language covernance which is represented in the IT system. For example, if we have a business system installation, it might depend on the system administrator's settings. For instance, we have German installations, but users might prefer to have another language.

Is this as well fine for you?

[Uriel-Sautron]

LGTM, tested good work.

[emersion]

Apart from these two minor issues, looks good to me, thanks for refactoring!

[emersion]

LGTM :)