Add unit tests for VideoRecorderAppState resize functionality

Tests cover:
- Initialization of VideoRecorderAppState
- Worker creation for different resolutions
- Worker eviction when fully drained
- isFullyDrained() functionality
- Non-blocking reshape behavior
- Worker reuse for same resolution

The tests use reflection to access internal state and verify the per-resolution worker pattern works correctly.

Co-authored-by: riccardobl <4943530+riccardobl@users.noreply.github.com>

Author: Copilot