feature: translation management

[DanceaVlad]

Description

Feature

What does this PR do?

Implements a way for admins to create/delete/modify languages, along with their translation keys and values

Code review focus

• Service error handling and permission, such as not allowing the english language to be deleted, not allowing the default translations to be modified...
• Liquibase changelog id and versions

Dependencies

This PR requires a frontend UI implementation.

Checks

• remove the Python script for generating the Liquibase changelog and its associated README.md and JSON file

closes GH-445

[lpandath]

@DanceaVlad
while integrating the translation management frontend with your backend, I encountered a couple of issues:

POST ${this.backendUrl}translations/language/${language} - when trying to create a language that already exists, it throws an EntityExistsException. It would be better if this endpoint was idempotent (return success if the language already exists) or returned a clearer error message.

DELETE - same, some deletion scenarios need better error handling.
to be able to work during development, I added a tmp mock service TranslationMockService in the frontend that tracks languages when backend operations fail, until this is resolved.

[GeoffreyKarnbach]

Great work! Please just change the few minor requests!

[GeoffreyKarnbach]

Talked with Valentin, maybe rather include this README content in the PR description, as we do not strictly need it here.

[GeoffreyKarnbach]

Also rebase the branch please, there were no conflicts for me when I did it locally!