Provide a default implementation for `ImageReader` and `ImageWriter`

[s1hofmann]

Short overview
With image matching code moved out of the main package nut.js should ship a lightweight default of a ImageReader and ImageWriter implementation

Use case
Currently one would still have to pull in the platform/node version dependent @nut-tree/template-matcher package to store e.g. screenshots to disk.
Lightweight alternatives which can be shipped with the main package should solve this