Function interpolateRectangle

interpolateRectangle(a: number[], b: number[], fraction: number): number[]
Interpolates between two rectangles represented as arrays of four numbers.
Parameters
- a: number[]
  The starting rectangle [x, y, width, height].
- b: number[]
  The ending rectangle [x, y, width, height].
- fraction: number
  The interpolation fraction (0 to 1).
Returns number[]
The interpolated rectangle.