* Report hot reload statistic

* Lints

* Introduce custom dimensions identifiers to track hot reload stats

* Allow passing a restart reason through to analytics

* Update to avoid overlaps with other code

* Remove TODO as this is the real live value

* Improve formatting + constant name

* enable lint unnecessary_new

* fix tests

* fix tests

* fix tests

This updates AppContext per the recommendations in #15352

Fixes #15352

Generate the "version" file from git tags.
Remove the old VERSION file and mentions of versions in pubspec.yaml files.
Replace the old update_versions.dart script with a new roll_dev.dart script.
Update "flutter channel".
Update "flutter upgrade", including making it transition from alpha to dev.
Update "flutter --version" and "flutter doctor".

* First version

* Prevent modification of .flutter during analytics test

* Pass in directory and override analyzer warning due to conditional import

* Review comments

* Get rid of static version methods which ignore the AppContext

* Review comments

* Review Comments

* Make branch behave the same as original implementation

* Fix tests

Previously, the usage analytics would generate a write to the user's
HOME directory during the Fuchsia build. We're tightening down the
environment in which we run the Fuchsia build, and these writes are now
more obvious.

This patch removes the usage analytics during the Fuchsia build,
avoiding the write to the user's HOME directory.

* report run target and if it is an emulator

* don't print debug

* rename parameter, remove unused variable

* fix test

* fix comment

* tweak from review, and fix analyzer error

* send custom parameters for the event, not the session

* fix mock

* use the +1 for usage

* send channel name as a custom dimension

* tweaks from review

* remove unused import

FlutterCommand.runCommand subclasses can optionally return a FlutterCommandResult which is used to append additional analytics. 

Fix flutter run timing report and add a bunch of dimensional data

`adb` can sometimes hang, which will in turn hang the Dart isolate if
we're using `Process.runSync()`. This changes many of the `Device` methods
to return `Future<T>` in order to allow them to use the async process
methods. A future change will add timeouts to the associated calls so
that we can properly alert the user to the hung `adb` process.

This is work towards #7102, #9567

This should make the message in Travis logs look better.

* enable crash reporting in flutter_tools

* fix analytics text; use relative paths

* fix test

Also, defer to test package for throttling (this will require a test
package update as well).

Also, add a lot more instrumentation to --verbose mode for tests, and
fix minor trivial things here and there, and add error handling in
more places.

Also, refactor how coverage works to be simpler and not use statics.

Update the analytics code.

* allow per-command analytics suppression

* rev the usage package dep

* shrink analytics message to < 80 chars

* catch line ending

* avoid sending analytics on ci systems

* review comments

* make the usage text more visible

* update the look of the usage text