Revert "[flutter_tools] Remove --no-sound-null-safety #3"

Remove no-shuffle from framework tests, part 1: easy cases

[flutter_tools] Remove --no-sound-null-safety #3

[Focus] Add run key command to dump the focus tree

Revert "[flutter_tools] Remove sound null safety flag (#123031)"

[flutter_tools] Remove sound null safety flag #2

This reverts commit 7c3088cf.

[flutter_tools] Remove sound null safety flag

Assert that runApp is called in the same zone as binding.ensureInitialized

Revert "Assert that runApp is called in the same zone as binding.ensureInitialized (#117113)" (#122830)

Revert "Assert that runApp is called in the same zone as binding.ensureInitialized"

Assert that runApp is called in the same zone as binding.ensureInitialized

implement override of toString() in order to print useful message in release mode as well as debug mode (#118263)

Added `_ErrorDescription.toString()`

* Fix typos

* lowercase animated & opacity

* Undo typo fix

---------
Co-authored-by: Michael Goderbauer <goderbauer@google.com>

* Ignore NullThrownError deprecation

* Fix whitespace

* Disallow dispose during listener callback

* addressing comment

* add comments to code

* Addressing comments

* fix test

* Fix test in preparation of the Dart VM switching to being null safe by
default.

* Fix analyze error.

* Format.

* Remove print.

* Fix analyzer lint.

* Fix warnings.

* Create enum for scheduler service extension names so they can be accessed from tooling

* fix two more strings

Landing on red to green the build.

* Use persistent hash map to store _inheritedWidgets

Instead of using a HashMap and copying it down the tree
which leads to quadratic time and space complexity
use a persistent data structure which can amortize
the cost by sharing parts of the structure.

The data shows HAMT based PersistentHashMap to be
5-10x faster for building _inheritedWidgets and
considerably more space effecient (e.g. bringing
amount of memory allocated when constructing
_inheritedWidgets in a tree with 150 InheritedWidget
down to 70Kb from 970Kb).

PersistentHashMap is slower than HashMap for
access: 2-3x in relative terms, but in absolute
terms we are only talking about ~0.2ns slow down
per access and various app benchmarks we run have
have not revealed any significant regressions.

The pubRoot directory interface is being changed to promote adding and removing directories