Migrated sample to more modern approach

[Evleaps]

Goal:
The current sample looks outdated. Beginners who use the sample for testing may face the need to adapt it to modern standards. This makes it harder to understand how the plugin works and how to configure it.

Action:
To reduce the entry barrier for configuring the plugin in a project and to improve its testability with the latest library versions, I made the following changes to the sample:

1. Moved dependencies to a .toml version catalog.
2. Replaced buildSrc with the build convention plugins approach, connecting custom modules via the plugins mechanism.
3. Updated all dependencies to their latest versions, including Kotlin 2.3.0.
4. Migrated all .gradle files to .kts.
5. Removed all warnings and deprecated functions.

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