When table metadata changes (e.g. due to queries launched in Superset or other external changes) the user has no convenient way to force a
refresh of the data. The metadata is persisted even across sessions and will never update if the user stays on the current tab.

This feature is a first step to make this experience better by adding a refresh button for each table that allows a manual refresh.

Future improvements:
- Automatically refresh when query is likely to change the metadata
- Refresh metadata from time to time