[MAINT] Refactoring metadata retained

[kaitj]

Describe the feature you'd like to see
Had some discussion about dropping some metadata that was irrelevant for the usage of afids_utils. Namely, storing the slicer_version does not provide any added benefit, and actually is only relevant to .fcsv files. Open to hearing people's thoughts before dropping this though.

[kaitj]

Some additional thoughts on this, one thing we would like to have / know is the space the AfidSet is in. There isn't a clear way of specifying this or extracting this information. It would be valuable for the metadata, but maybe we leave this out until there is a clearer solution for this.

@ataha24, should have a discussion around metadata so we can push try to push some of this development forward.