Save mapcodes/locations as favourites

[sds100]

• Have favourites screen
• store favourites without mapcode
• Ask for name of favourites. Set to address by default.
• Button to delete favourite
• Button to rename favourite
• Button to share favourite
• Show mapcode as subtitle in favourite list item
• Clicking a favourite should go to it on the map
• Have add favourites button below lat/lng
• show favourites as markers on the map
• Disable "view favourites" button if no favourites. Show a snackbar saying "Create a favourite first!"
• Put icon next to address for saving location.
• Make button remove favourite if location is already saved.
• show confirmation dialog before removing favourite