When using --use-application-binary:

- [x] Stop flutter run from checking for a pubspec.yaml in current directory
- [x] Stop flutter run from invoking pub get
- [x] Set 'shouldBuild' based on --use-application-binary
- [x] Stop requiring 'lib/main.dart' to be present before running.
- [x] Stop building an FLX when launching on Android

* refactor _run to runCmd

* replace requiresProjectRoot getter with call to commandValidator

* replace requiresDevice getter with call to findTargetDevice

* trace command requires a debug connection, not a device

* inline androidOnly getter

* rename command methods to verifyTheRunCmd and runCmd

* move common verification into BuildSubCommand

* rename deviceForCommand to device

* rename methods to verifyThenRunCommand and runCommand

When flutter run is used on a Mac and no devices are specified or attached, suggest launching a simulator first. Fixes https://github.com/flutter/flutter/issues/5674

* improve device matching error message
fixes https://github.com/flutter/flutter/issues/5675

* update the cache earlier

* add documentation

* make flutter run work with a pre-built apk

* refactor to remove the buildDir param

* This reverts commit 5e7e7b6e.

* default to lib/main.dart

This reverts commit 32ad81c8.

* refactor the --resident run option into a separate file

* update daemon to run --resident apps

* re-plumbing daemon start

* send app logs

* update tests

* review changes

* fix test runner

* remove PackageMap.createGlobalInstance; rely on the ctor

* review comments

* dissallow -release mode on emulators

* have the help text print the default mode

Artifacts from local engine builds will be found based on the --local-engine flag

Host tools can be found in the artifact cache directory for the host platform.
If a developer wants to use a local engine build instead, then provide an
--engine-build flag that selects the specific engine build variant.

* make the usage text more visible

* update the look of the usage text

* fix analysis errors

* review comments; fix test

* re-add an export for debugPrint

Also update the engine to a build where these tools have been uplaoded

* add google analytics

* send in the run target type

* track device type targets

* use the real GA code

* review comments

* rev to usage 2.0

* rev to 2.2.0 of usage; add tests

* review comments

This is currently hidden for development use.  It will select artifacts from
the android_{Debug,Release}_Deploy output in a local engine build.

* rename the --develop option to --debug

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

* use the new cache code to locate more artifacts

* add todo

* review comments

* run pub for analyze and test

* don't run pub when doing repo analysis

* move logic for when to run pub into the commands

* re-write ternary expression

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

* move the engine download code to dart

* fix populating the bin/cache/pkg dir

* add cache.dart to help manage the cache dir

* sp

The .packages file is replacing the packages directory of symlinks.

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