Fix AvalancheCenterSelectorModal Error State

[kevinherdez]

• Fix Avalanche Center Selector Modal Showing Error #1138

This fixes an issue I ran into when I didn't have good reception. It's possible for the network calls used by the AvalancheCenterSelectorModal to fail while the map loads fine. This causes the error state for the modal to be shown even if the modal isn't shown

The fix moves the error state inside the modal itself so that it's only rendered, if the modal needs to be rendered (based off the visible and loading flags)

Error inside the modal

I also cleaned up the modal in general:

• Removed SafeAreaProvider and SafeAreaView in favor of safeAreaInsets that was already being used in the view
• Removed the top level View. The VStack taking up 100% of the height fills the view by itself
• Remove the View that was needed "to paint the very bottom of the screen white". I just changed the background colors in the content so I could achieve the same effect