Fail gracefully when circles have invalid radius

[LucaMarconato]

The PR #653 breaks compatibility with older datasets. We should address this and have a way for the framework to fail in a way that the user is prompted in what to do.

[LucaMarconato]

Here a better solution would be to have a migration tool which loads recomputes the radius of the circles and replaces the old shapes element with the new radius.

[LucaMarconato]

I think we should proceed as follows:

• in the longer term, we should consider having a migration tool to deal with cases like this
• for the moment we should keep throwing the error raise a warning and add "If this are seeing this error upon opening Xenium 2.0 data, please see this link for a solution: link_to_github_discussion". Then we should put a global setting that relaxes the validation against nan and in the discussion we should ask the user to enable this setting. The users will then be able to read the data, call to_circles() from the cell polygons get the correct circles from the table and save the data with write_element(). We should also tell the user that if regenerating the data is an option, they can just re-run the script.

[LucaMarconato]

I have addressed this with #658 and the discussion #657.