* 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

* add a --deploy flag to build apk

* update command description

* use an enum instead of a bool param for build variants

* rename buildForDeploy flag to buildVariant

* review comments

Do not check for an existing package map if a command is going to run "pub get" to update the package map (#3202)

Also remove a redundant check for the --pub option in the run command

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

All artifacts for iOS are universal.

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

Fixes #2517

Previously we were ignoring the return code and continuing.

@devoncarew

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.

Runs a test app and a driver test simultaneously, then stops the app.

Usage:

```
flutter drive --target=/path/to/test/app.dart
```

This command will look for `/path/to/test/app_test.dart` by
convention. We will expand into other ways of discovering tests in the
future.

This removes a step that can cause trouble.

Fixes #1904

Previously we'd always stop org.domokit.sky.shell. If an
AndroidManifest.xml exists, we'll use the activity specified in there
instead.

flutter start no longer depends on a pre-built SkyShell.apk. It builds a
new one, as long as an AndroidManifest.xml exists.

We rebuild the .apk every time either AndroidManifest.xml or
flutter.yaml changes.