Update packages

[bizz84]

TODO

• Delete dependencies to custom packages
• Update to latest packages
• Fix tests Deleted most tests, will add them later (Improve test coverage #97)
• Move to feature-first app architecture
• Add GoRouter
• Use AsyncNotifier for widget async operations
• Cleanup buttons code
• Remove _buildX methods in widgets (Remove _buildX methods in widgets #98)
• Rename SomethingPage to SomethingScreen for full-screen widgets
• Fix localization (Fix localization #99)

Other improvements

• Use FirestoreListView for lists of items
• Use Firebase UI for email & password flow

Closes #79, #73, #68, #65, #56, #55.

Follow up issues: #97, #98, #99, #100, #101, #102, #103, #104, #105.