* 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

We decided that redefining the default for templates was premature. We're going to go back to having "module" in experimental land again, and we'll try again when we have the feature set fully baked.

This keeps the writing of the .metadata files, and writing the template type to them, because that was a good improvement, and there are still a bunch of added tests that improve our coverage.

This renames the "module" template to the "application" template, and makes "application" the default. The existing "app" template is now deprecated.

flutter create also now recognizes the type of project in an existing directory, and is able to recreate it without having the template type explicitly specified (although you can still do that). It does this now by first looking in the .metadata file for the new project_type field, and if it doesn't find that, then it looks at the directory structure. Also, the .metadata file is now overwritten even on an existing directory so that 1) the project_type can be added to legacy projects, and 2) the version of Flutter that updated the project last is updated.

I also cleaned up a bunch of things in create_test.dart, added many more tests, and added an example test to the test/ directory in the generated output of the application template.

Fixes #22530
Fixes #22344

* enable lint unnecessary_new

* fix tests

* fix tests

* fix tests

All temporary directory start with `flutter_` and have their random component separated from the name by a period, as in `flutter_test_bundle.YFYQMY`.

I've tried to find some of the places where we didn't cleanly delete temporary directories, too. This greatly reduces, though it does not entirely eliminate, the directories we leave behind when running tests, especially `flutter_tools` tests.

While I was at it I standardized on `tempDir` as the variable name for temporary directories, since it was the most common, removing occurrences of `temp` and `tmp`, among others.

Also I factored out some common code that used to catch exceptions that happen on Windows, and made more places use that pattern.

* 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

It was causing problems rolling Flutter into Fuchsia

* re-enable lint unnecessary_const

* remove trailling whitespaces

* remove unnecessary const (after merge)

This reverts commit cc1cf13e.

* Fix packages tests when run off bots

* Tweak dependencies to make bots happy

* Review comment

Merging on red tree to get back to green.

This reverts commit b3e4976c.

Moves MockProcess, MockStdio and a few other useful mocks from
packages_test.dart to common/mocks.dart. These are useful for testing
code with interactive IO.

This adds a new constructor to MockProcess to provide additional flexibility.

See https://github.com/dart-lang/pub/issues/1714

* Enforce valid package names on flutter create

Fixes #9564

* refactor

* fix other tests

`all.dart` is no longer needed. Furthermore, it causes tests to
be skipped, or to silently fail to run anything.

Fixes #7941

This removes direct file access from within flutter_tools
in favor of using `package:file` via a `FileSystem` that's
accessed via the `ApplicationContext`.

This lays the groundwork for us to be able to easily swap
out the underlying file system when running Flutter tools,
which will be used to provide a record/replay file system,
analogous to what we have for process invocations.

* Remove the workaround that pinned args to v0.13.6
This reverts most of the changes in commit 6331b6c8
* throw exception if exit code is not an integer
* rework command infrastructure to throw ToolExit when non-zero exitCode
* convert commands to return Future<Null>
* cleanup remaining commands to use throwToolExit for non-zero exit code
* remove isUnusual exception message
* add type annotations for updated args package

* implement flutter packages get/upgrade command
* alias flutter pub
* refactor findProjectRoot for use by multiple commands

fixes https://github.com/flutter/flutter/issues/4994