Add interruption events

[AHGIJMKLKKZNPJKQR]

Added interruption events for agents:

1. InterruptTrack - cancels a single track

These events aim to allow users to cancel previously sent audio buffers from being played.

Example:

1. A user starts talking while an agent is talking.
2. The agent's builtin VAD notices that the user started talking and emits audio.interrupted event, which stops generation of audio.
3. When handling this event, the agent sends an InterruptTrack event to fishjam on the corresponding track.
4. Fishjam drops already queued buffers, to prevent them from being played

[linear]

FCE-1972 Handle agent interruptions