"Clear up space" feature to remove synced photos and submissions

[gino-m]

Photos and submissions currently stay on the device until the survey is removed or app is uninstalled. We should offer the user a way to see how much space each survey occupies on the device and offer a way to remove synced data. We should also link them to the offline areas page so they can remove data they don't need there as well.

@jo-spek @andreia-ferreira @vittorino

[jabramowitz5]

• I agree that a way to see how much storage per survey is being used would be useful
• I would lean towards having already synced data only be available when back online (data on device removed upon sync) --> this seems logical with when a data collector may be going back through collected data when they return to internet connection rather than while still in field (and if they are still in the field they can view the data prior to syncing) --> I assume this would mean a data collector could view all of their own (and only their own) data collected for a given survey on their device while connected to internet