Provide a better way to serialize and represent arbitrary objects in the Variable Explorer

[dalthviz]

Originally posted by @dalthviz in https://github.com/spyder-ide/spyder/issues/20671#issuecomment-1466752966

There are limitations in the way the Variable Explorer currently works. If you are using a custom/external interpreter is possible that some variables can't be open. This situation comes from the base Spyder installation missing the packages installed in the custom/external interpreter env which causes the imposibility to deserialize variables.

Creating this issue to follow-up into improving this situation

[jitseniesen]

As noted in the issue above, the GeoDataFrame type as provided by geopandas is another practical example where we currently fall short.