* WIP on web plugin registry
* WIP on registering plugins
* WIP on web plugin registration
* Only generate `package:flutter_web_plugins` imports if plugins are
defined
* Add parsing test
* Add documentation
* Fix analyzer warnings
* add license headers
* Add tests for package:flutter_web_plugins
* Run `flutter update-packages --force-upgrade`
* Fix analyzer errors
* Fix analyzer error in test
* Update copyright and remove flutter SDK constraints
* Enable tests since engine has rolled
* add flutter_web_plugins tests to bots
* Create an empty .packages file for WebFs test
One of our linux/android Moto G4 has alerts (emergency, amber, etc.)
turned on. That's probably the cause of the flakiness. I've turned it
off.
Let's mark this as non-flaky and see if it's fixed. If not, I'll move it
to mac/android and see if that fixes the flakiness.
I think the most important thing to do right now is to mark it as
non-flaky so those who really break the test could get a notification.