Creates a new (hidden) flutter command 'ide-config' that will create and/or update
existing .iml files and some files under the .idea directory, as well as
removing existing *.iml files and the .idea directory.

It also:

 * Adds *.iml to the .gitignore
 * Removes existing .iml files from the repo, and moves them to the
   packages/flutter_tools/ide_templates/intellij directory.
 * Adds a flag to ide-config ('--update-templates') that will take any new .iml
   files in the flutter tree and add them to the existing templates.
     - If --overwrite is also specified, then all existing templates will also
       be overwritten with the contents from the flutter tree, and any that have
       been deleted from the flutter tree will also be removed from the
       templates.
 * Added new run configurations for all existing app targets that will now also
   be automatically added to IntelliJ.
 * Setting up the environment also includes setting the coding style guidelines
   and the git VCS.
 * Note that after this PR lands, Flutter developers will need to run it once to
   re-create the .iml files and configuration files that have been removed.

After this PR lands, .iml files will no longer appear in the untracked files
section for git.

If we fail to bind to IPv4 loopback, try IPv6. Some hosts only support IPv6,
causing the test in vmservice_test.dart to fail, since it couldn't find an
available port.

* Get rid of static version methods which ignore the AppContext

* Review comments

* Review Comments

* Make branch behave the same as original implementation

* Fix tests

* Implement MultiFrameImageStreamCompleter

* only decode frames while there are active listeners

* review comments followup

* multiply animation frame timer duration by time dilation

* lint

* tweak the text for the 'elements didnt reload' message

* review comments

* prefix items with a list char

* add a hostIsIde param instead of the isDaemonMode top-level function

* add a trailing comma

* Use IKG for restarts, use IKG with ProtectedFileByteStore.

* Fix comment, add end of file newline.

* Remove unused import

* try some lints

* remove avoid_returning_this rule

* executable.dart#main() depends on runner.dart#run()
* Refactor code such that non-commands don't depend on commands.

No code was actually changed in this PR - code was merely moved from
point A to point B.

This reverts commit 5939ff45.

UnconstrainedBox will allow its child to size itself as if it had no constraints, and then attempt to fit around that object, until its own constraints are exceeded, in which case it will clip and display an overflow warning.

I also factored out DebugOverflowIndicator, which will draw overflow indicators on containers which overflow but aren't expected to.

* fix with first part of test

* Test without reshifting

* Let sliver fixed extend list also handle disappearing top items.

I'm not really sure how to test this without a reference test, since
eventually we want to move this to a font feature and thus the obvious
test (looking for the Transform widget) isn't really valid.

* address unused element issues and new warnings

* add a missing return

* enable lint prefer_asserts_in_initializer_lists

* enable --assert-initializer