* add trailing commas on list/map/parameters
* add trailing commas on Invocation with nb of arg>1
* add commas for widget containing widgets
* add trailing commas if instantiation contains trailing comma
* revert bad change
* Upgrade everything except matcher.
* Roll matcher (and test)
* Adjust tests that depend on flutter:test directly to depend on a shim
* Require use of package:test shim and remove other references to package:test
This changes the publishing of archives so that it happens on the chrome_infra bots when they build a packaged branch instead of as part of the dev_roll process.
It uses the tagged version in the branch, and leaves the git repo that it clones checked out on the branch and hash used to build the package.
It updates metadata located at gs://flutter_infra/releases/releases_.json (where is one of macos, linux, or windows) once published, since it would be complex to do the proper locking to keep them all in one shared .json file safely.
A separate [change to the chrome_infra bots](https://chromium-review.googlesource.com/c/chromium/tools/build/+/902823) was made to instruct them to build packaged for the dev, beta, and release branches (but not master anymore).
