Updates management UX feedback improvements

[local-optimum]

A couple of scenarios that it would be good to provide feedback to the user on in the 'Manage' page:

• When trying to update a snap that is currently running, clicking the update button does nothing and provides no user feedback that the app must be closed to update, this is clearly messaged when trying snap refresh in the terminal so we should be able to provide a GUI equivalent
• After applying a number of updates the apps in the updates available section did not update until I did a manual refresh, in Windows or other stores you would expect each app icon to move into 'installed and updated' once their update process has completed.