add in ability to download image from metaspace

Currently the metaspace retrieval fails to get the image itself. We need to investigate [this function](https://github.com/metaspace2020/metaspace/blob/c7dae82622150c737660e1d5eb6d649b3c86a76d/metaspace/python-client/metaspace/sm_annotation_utils.py#L1238) to download the underlying image so we can add it to the spatialExperiment object in one step. 