Update CaptureBasic sample with Mode selection UI

Adds ImGui interface for runtime device and mode selection. Users can
choose capture devices from a dropdown and select specific modes
(resolution, framerate, format) or use automatic mode selection.

Displays current capture details including resolution, connection status,
frame rate, codec, pixel format, and color model. Demonstrates the new
Mode-based capture API with practical usage examples.

Author: andrewfb