Bump Dart SDK to 1.17.0-dev.3.0.

Keeping up with the Joneses!

Fix crash installing onto certain Android devices

* use vendored dart sdk; check the expected version of flutter

* search up directories looking for the flutter root

Turn on SDK summaries in flutter analyze.

The latest dev build has stable summaries so we should start using them.

(Also ensures that analysis options are propogating to the SDK analysis context --- see:  https://github.com/dart-lang/sdk/issues/26129.)

* send ext.flutter.exit

* listen for help restart, quit

* refactor into a separate class

Fixes #3835

Fixes #3835

Update flutter_tools for the "unoptimized" engine build flag and the new output directory naming scheme (#3832)

Upgrade gradle files for Android Studio 2.1

Fixes #3833

* Use mojo clipboard service for copy/paste toolbar.

BUG=https://github.com/flutter/flutter/issues/1567

Fixes #417

Remove gratuitous pub resolver from flutter analysis.

Bump Dart SDK to 1.17.0-dev.2.0.

Package mapping is already done by the `PackageDependencyTracker` so this extra check is at best not needed.  (At worst could cause an unneeded and costly call to `pub list-package-dirs`!)

Analyze update to use in-memory package map.

Fixes #3795

Updates the analyze command to pass a package map to analysis rather than a file path.

This allows us to avoid creating a needless temporary `.packages` file and host directory and saves us a trip to disk to retrieve the contents when building our URI resolvers for analysis.