Implement new splash screen

We have a new splash screen for mobile. This should be displayed while we clear the cache, pull in feature flags and update the offline data needed to run the app

Dark mode: https://design.minds.com/hosted/mobile/michael/mobile%231642-navigation/ Light mode: https://design.minds.com/hosted/mobile/michael/mobile%231642-navigation/#artboard8

• New light bulb splash screen
• light mode
• dark mode
• e2e tests to make sure it transitions and loads our data appropriately