Switch Spectrogram to utilizing pre-signed URLS

[BryonLewis]

The current system is creating a local image (and for non-compressed) storing in minio and then converting it to base64 so it can be transfered to the front-end. This was just done initially to have something to display. It would make more sense to utilize pre-signed URLs.

• Use the default_storage.url(fileField) like in: https://github.com/Kitware/batai/blob/main/bats_ai/core/views/recording.py#L104
• convert endpoints for spectrogram to utilize a pre-signed URL instead of the base64 text
• Update the client to utilize the pre-signed url instead of base64.

Compressed View

It may make sense to make a compressed view that is also stored in MinIO. We may just have it updated when annotations are edited so it has some sort of caching system.

[BryonLewis]

The system is using presigned URLs now that are stored in MinIO instead of directly generating the spectrogram every time.
This can be seen here: https://github.com/Kitware/batai/blob/main/client/src/api/api.ts#L111
Also here in the initalieViewer function for the geoJS layer it uses the URL directly to render the image:
https://github.com/Kitware/batai/blob/main/client/src/components/geoJS/geoJSUtils.ts#L117

[BryonLewis]

fixed in #104