Feature: Add endpoint to delete a number of SoundFileSources

[Joltras]

Describe the feature

The backend should provide a DELETE endpoint for the SoundFileSource that accepts multiple element IDs to delete in a single request. This would allow batch deletion of multiple objects and prevent the need for sending many individual delete requests.

Why is this feature important to you?

This feature enables the frontend to delete multiple entries at once, improving efficiency and reducing unnecessary network requests.

Additional context

It should be considered whether the endpoint should accept the full DTO or if providing only the DTO IDs would be sufficient.