prevent same languageTags from being added

[felixhaeberle]

Context

Currently, it is possible to add the same languageTag twice.

Proposal

Prevent it.

[NilsJacobsen]

This is part of the validation milestone.

[NiklasBuchfink]

@nils.jacobsen FYI for this milestone:

https://github.com/opral/monorepo/blob/59825aef17f4a9cbfd3ca4605277b361e0b8a91e/inlang/source-code/editor/src/pages/%40host/%40owner/%40repository/Layout.tsx#L326-L364

[samuelstroschein]

seems like it should be a lix validation rules. better to have one universal validation rule/system to reduce effort of building and maintaining duplicate validation logic. (the validation of avoiding duplicate locales is universally useful)

agree to add to the lix validation rule project?

[NilsJacobsen]

For some things that might make sense. But I'm not sure if I can answer that already. Need to think through it when we get back to it.