Refactor point types ` { x, y }` to the proper unified point type in `@excalidraw/math`

Goal: Have a unified point type system across the codebase.

• Create missing point type ViewportPoint = [x, y] in @excalidraw/math
• Create unified point type GenericPoint in @excalidraw/math
• Refactor point generic function type parameters to extend GenericPoint where applicable
• Refactor object point types (i.e. { x: number, y: number } to use GlobalPoint, LocalPoint, ViewportPoint or a combination as applicable

Note: Watch out for rough-js point types, which are also [x,y] but cannot be refactored. Avoid type casting as much as possible.