Delete / rename old values when changing field names for Settings fields

[PodsBot]

Delete / rename old values when changing field names for Settings fields submitted via Slack by sc0ttkclark

[sc0ttkclark]

This needs an elseif statement to cover settings pods, it should rename the old option names to the new option names (format: {pod_name}_{field_name})

https://github.com/pods-framework/pods/blob/master/classes/PodsAPI.php#L2513

While you're in there, please add an additional pods_query and update $prepare so you prefix the names of those fields with '_pods_' so we cover those cases there too:

https://github.com/pods-framework/pods/blob/master/classes/PodsAPI.php#L2502

[pglewis]

Executive decision that this shouldn't hold up 2.5.3 (nothing breaks, it just leaves detritus), so punting to the next milestone.