`WSIReader` support for caching with cuCIM backend

`cuCIM.CuImage` object has the capability of cache handling but it is disabled by default so `WSIReader` is not taking advantage of it. It would be beneficial for some training pipelines to support caching. Here is an explanation of caching in cuCIM and how to work with it: https://github.com/rapidsai/cucim/blob/branch-22.10/notebooks/Welcome.ipynb