Clean up dependencies across packages (#2585)

Drop dep on pkg:collection, use new bits in Dart 3.0
Fixed very old dep in navigation_and_routing – bug was fixed long ago

experimental/web_dashboard/.gitignore

@@ -30,8 +30,5 @@
 .pub/
 /build/
 
-# Web related
-lib/generated_plugin_registrant.dart
-
 # Exceptions to above rules.
 !/packages/flutter_tools/test/data/dart_dependencies_test/**/.packages

experimental/web_dashboard/pubspec.yaml

@@ -8,7 +8,6 @@ environment:
 
 dependencies:
   cloud_firestore: ^5.0.1
-  collection: ^1.16.0
   community_charts_flutter: ^1.0.2
   cupertino_icons: ^1.0.0
   firebase_auth: ^5.1.0