feat(lang): add Slovenian display language

[avidenic]

Description

• added support for Slovenian display language

To-Dos

• Successful build yarn build
• Translation keys yarn i18n:extract
• Database migration (if required)

Issues Fixed or Closed

• Fixes Add Slovenian language to Weblate #3765

[jordanjones98]

It is worth noting that this does not add Slovenian to weblate, this just allows it to be selected in the lang dropdown. That being said I assume you added the sl.json file so build will pass before weblate starts to manage it.

Edit: I see in weblate that it says you need to add the JSON file first, so I get what you did here now. Sorry!

[avidenic]

@jordanjones98 I've not used weblate before, but it's great that it seems I got it right. I've also updated this branch with develop.