fix: properly release canvas/gl contexts when component unmounts

This fixes an issue that after reloading pixi-based visualizations for more than 16 times, the browser throws warnings.

Took a bit longer, matrixvis needed to be refactored a bit (app using useMemo instead of a global var, and subsequent changes), otherwise app would not even exist at the point of unmounting, hence no destroy method can be called. All done now though 🙂