* move driver create test to the flutter_tools package

* review comments

* allow flutter create to re-gen over an existing project

* add a regression test

* rename the --develop option to --debug

* fail if both --debug and --deploy are specified

* download android-arm-deploy

* wire up --deploy to android-arm-deploy

* fix interpolation

* use the new cache code to locate more artifacts

* add todo

* review comments

* more terse flutter upgrade

* fix an issue when updating and the engine update code has changed

* call flutter precache; add a --no-color hidden option

* fix a lint related to getters/setters

* Add validity checks to create

* Adjust indent

Add a command that can capture a Skia picture of a Flutter frame and send it to a file or skiaserve debugger (#3165)

Driver returns exit code 0 even when tests fail. This commit fixes it by
propagating the exit code set by `package:test`.

All artifacts for iOS are universal.

Instead, require an AndroidManifest.xml and always build an APK.

Fixes #2517

Test that flutter analyze catches no error if two imported libraries
have the same name.

Also, make tests know how to find the flutter root and fix style in one
test to be consistent with the rest of the file.

And fix a zillion omissions this uncovered.

https://github.com/flutter/flutter/issues/2368

flutter start's method of finding devices to run the app on is not suitable for flutter drive.

This commit also refactors several tool services to allow mocking in unit tests.

"flutter create" adds option `--with-driver-test` that adds
dependencies to `flutter_driver` in `pubspec.yaml` and creates
a basic driver test runnable via `flutter drive
--target=test_driver/e2e.dart`

"flutter drive" new options:

- `--keep-app-running` tells the driver to not stop the app after tests
  are done
- `--use-existing-app` tells the driver to not start a new app but use
  an already running instance