Support loading behaviour classification annotations

[sfmig]

Is your feature request related to a problem? Please describe.
It would be nice to support behaviour classification annotations, and read it as a movement "events" dataset.

Describe the solution you'd like
We should support relevant formats.

• a popular tools seems to be BORIS
• we could support VIA-3 too (since we already support it for annotations and seems quite flexible) - see a description of the output JSON format here and a demo here. The temporal segments only (so no project settings) can be exported as csv too, this is probably the easiest way to start.

Describe alternatives you've considered
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Additional context
Relates to #16

[Edu92337]

Hi @sfmig I recently implemented a similar function in movement (PR #757) that converts pose data to bounding boxes. Since ethology already depends on movement, would it make sense to use that implementation directly, or would you prefer a wrapper/adaptation specific to ethology's bout-based data structure?

Happy to help with either approach!