Migrate to dart_flutter_team_lints v2.1 (dart-lang/watcher#153)

- Fix new lints.
- Deduplicate lints in local config.
- Add some missing generic types on futures and stream controllers.
- Fix a typo in a test.
- Remove unnecessary library names.
21 files changed
tree: 9e200e2e931199e5e66d4260c825f023be3445e6
  1. pkgs/