Feature Request: Support for Uploading OPUS Audio Files

[Pucciano]

Is your feature request related to a problem? Please describe.
I would like to request the implementation of support for uploading OPUS audio files in Label Studio. This feature is necessary to ensure compatibility and streamlined processing of OPUS audio format, which is widely used for its high quality and efficient compression.

Describe the solution you'd like
To implement this feature, please refer to the patch available at: Pucciano@c3b2391

Describe alternatives you've considered
An alternative is to convert OPUS audio files to WAV. This can be done with Audacity's batch processing or with a custom Python script using pydub. However, this change allows uploading and processing OPUS audio files without conversion. But converting files takes some time and also disk space.

Steps to Reproduce

1. Attempt to upload an OPUS audio file in the current version of Label Studio.
2. Observe that the file format is not supported.

Additional context
Adding support for OPUS audio files will enhance the versatility of Label Studio, allowing it to handle a broader range of audio file types. This feature is essential for projects that require high-quality audio annotations. This is built and tested with WhatsApp voice memo files.