* Add a check in case the flutter directory in .packages no longer exists. Clean up and prompt user

* Update documentation to use flutter packages get for end-users instead of flutter update-packages.

* Merge missing sdk error with the multiple sdk error. They're really the same thing.

* Use flutterPath in both checks.

* Change file_system’s copy folder to copy director which takes into account the file system

* Test support files

* Add test and split into 2 messages again.

* Move tests to run in memory file system's copy. Tested with dev/bots/test.sh

This ensures that accidental usages of dart:io's
file API don't creep in over time.

This removes direct file access from within flutter_tools
in favor of using `package:file` via a `FileSystem` that's
accessed via the `ApplicationContext`.

This lays the groundwork for us to be able to easily swap
out the underlying file system when running Flutter tools,
which will be used to provide a record/replay file system,
analogous to what we have for process invocations.

This argument will enable mocking of os-layer process invocations,
where the mock behavior will come from replaying a previously-
recorded set of invocations. At the point of process invocation,
the key metadata for the invocation will be looked up in the
recording's manifest, and iff a matching record exists in the
manifest, the process will be mocked out with data derived from
the corresponding recorded process (e.g. stdout, stderr, exit code).

* Add --record-to option to flutter tools

This option will cause flutter tools to record all process
invocations that occur and serialize their stdout and stderr
to files that get added to a "recording" ZIP file. This is
part of an effort to be able to test flutter tools in a hermetic
environment.

As a side-benefit, this recording should prove an excellent
attachment to any bug report.

* Remove the workaround that pinned args to v0.13.6
This reverts most of the changes in commit 6331b6c8
* throw exception if exit code is not an integer
* rework command infrastructure to throw ToolExit when non-zero exitCode
* convert commands to return Future<Null>
* cleanup remaining commands to use throwToolExit for non-zero exit code
* remove isUnusual exception message
* add type annotations for updated args package

With the old policy the most recent log would not be printed until the next
log is produced (which may be indefinitely).  This change prints logs
immediately along with a time delta since the previous log.

* show hidden flags when showing verbose help
* flutter -v show verbose help

Do not throw when resolving a local engine if the .packages map does not include the flutter package (#5519)

It can cause trouble if the user has a newer Android SDK installed normally.
Instead, just use the normal Android SDK.

* Fix `flutter upgrade`

* Fix builds on iOS

This prevents multiple simultaneous runs of the analyzer from stomping
over each other (e.g. multiple runs of 'update-packages'). Certain
long-lived commands (like analyze, run, logs) are exempted once they've
done enough work to be safe from most stomping action.

This still doesn't make us entirely safe from craziness, e.g. if you're
half way through an 'update-packages' run and you call 'git pull', who
knows what state you'll end up in. But there's only so much one can do.

Fixes https://github.com/flutter/flutter/issues/2762

Also, make it clear the screen between results so it's more obvious
what's going on when you have new results (especially when you have
fixed everything).

* 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

* resolve symlinks in paths to flutter

* review comments

This reverts commit 8f69cccc.

This passes the information through Xcode to the `flutter build aot` call via
the environment so that it picks up the right artifacts.

Fixes #4186

* rebuild when the build type changes

* handle local engine builds

* also check the timestamp

* allow per-command analytics suppression

* rev the usage package dep

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.

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

* search up directories looking for the flutter root

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

* avoid sending analytics on ci systems

* review comments

* 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