build(gradle): add build-time validation for prefabs and JSON assets #4986

[mmruii]

This PR implements build-time validation for all JSON-based assets (such as .prefab, .block, .ui, and .json files) in both engine and modules.
It introduces a custom Gradle task that parses each asset and fails the build with a descriptive error if any file contains malformed JSON.

Modified files:

ValidateJsonAssets.kt:
New Gradle task that validates JSON assets at build time.
build.gradle.kts:
Adds the org.json dependency and test dependencies for the new task.
terasology-module.gradle.kts:
Registers the validation task for all modules and hooks it into the build process.
build.gradle.kts:
Registers the validation task for engine assets and hooks it into the build process.
build-logic/src/test/kotlin/org/terasology/gradology/ValidateJsonAssetsTest.kt:
Unit tests for the validation task, covering valid, invalid, and missing asset scenarios.
How to test:

Run a build (./gradlew build) with valid and invalid JSON assets to confirm that the build fails on malformed files and succeeds otherwise.
Run the included unit tests for the validation task.
Outstanding before merging:

Review if additional asset types should be included.
Documentation update if needed.

Closes #4986

[Cervator]

Hi there, welcome, and thank you 👍

It looks like you already triggered a good looking test in the Jenkins build :-)

* What went wrong:
Execution failed for task ':engine:validateJsonAssets'.
> Found 1 invalid JSON asset(s):
    - /home/jenkins/agent/workspace/Terasology_engine_PR-5326/engine/src/main/resources/org/terasology/engine/assets/ui/menu/moduleDetailsScreen.ui: Duplicate key "layoutInfo" at 20601 [character 37 line 333]

That's encouraging! Although it does need a quick fix in that actual file - great example though 😁

And I see tests, also good!

I'll try to find time to test and review a bit later, but one thing that stuck out is implementation("org.json:json:20240303") - it could just be a copy pasted snippet, I find that using AI tools tends to arbitrarily pick a version unless you make it go look for the latest. It does appear like there are newer versions of that library, so we should probably aim for the latest (just a few months old)