Adds new LUCI targets in bringup mode to run all possible Dart unit tests in Chrome.
This is a new test (see linked issue), not a port of a Cirrus test, so it involves changes to tooling and packages:
- The tooling now accepts an explicit platform. The default behavior if none is provided is the previous behavior of running in VM for everything but web plugin implementations (since that's convenient locally).
- The tooling now has a basic understanding of `dart_test.yaml` `test_on` directives, to know when to skip.
- Packages that don't support web have opt-out files.
- Packages that do support web but have a few tests that fail on web have those tests opted out.
- Packages that do support web but have a lot of failures on web have temporary opt-out files with TODOs + issue links.
Most of https://github.com/flutter/flutter/issues/128979
Adds aliases for all commands that put the verb first, since currently they are inconsistent which can make it hard to remember (in particular, I often write `check-foo` instead of `foo-check` when running locally, and it fails).
Also does the long-overdue renaming of `test` to `dart-test`, since we now have `native-test`, `custom-test`, etc. `test` continues to work as an alias for individual muscle memory.
