Just a docs-only improvement in EditableText and text input.

[flutter_tools] eagerly set asset directory path, cache flutter views, simplify error handling (#68978)

Performs some small cleanup on the hot reload code path.

- Combines nested try/catch into single try catch, update on clause now that package:vm_service is used and Map does not need to be caught.
- Cache FlutterViews for the lifetime of the hot reload method handler
- Set asset directory path once during startup and remove conditional set during hot reload

A new widget that chooses an item from a list based on text input. Just the core widget, with Material and Cupertino versions to come.

This reverts commit 05ab0eba.

This reverts commit 19ce7a86.

This reverts commit 3ecac303.
Co-authored-by: Dan Field <dfield@gmail.com>

Migrate flutter_driver to use package:vm_service

* [flutter_tools] simplication of application store logic

* maybe return null

* fix install tests

* Clean up imports

* revert windows test

* remove unused import

The tool observes a large number of unhandled exceptions during the file copy portion of flutter create. it is difficult to tell whether the permission issue is caused by the source/destination, or whether it is due to a bug in dart:io.

To work around this, implement a permission check for both the source and dest files. If either fails, the tool can exit with a more specific message.

If these checks pass, then perform the actual copy. If the copy fails, fallback to manually copying the bytes

* [flutter_tools] add package_config.json to analyze_once_test.dart

* update pinned null safety deps

* run update-packages

* add http dep to devicelab package

* rerun update-packages

Overhaul of flutter drive in order to deliver a better experience, namely:

* flutter run and flutter drive now share more flags, so code paths that were previously only testable on run are now testable on drive.
* Removes web-initialize-platform as this is no longer used
* flutter drive correctly sets up a logger that shows native exceptions, by connecting to the vm service.
* VM service connection now provides access to memory info without launching devtools (only for debug/profile mode)

Web changes

* Passes on the one test in the repo, otherwise the webdriver code has been isolated as much as possible

Additional NNBD related bug fixes:

No longer passes --enable-experiment to the test script. (FYI @blasten ). earlier we might have assumed that the flutter gallery benchmarks would be migrated along side the app and flutter driver, but only the app under test needs to be migrated. The test scripts should never be run with the experiment.

e2c375084 Roll Dart SDK from 1897e02f5b1c to 96369fde1083 (2 revisions) (flutter/engine#22113) (#69002)

* refactor update_icons

* fix trailing space

* address feedback

* Rename to _iconsMirroredWhenRTL

This reverts commit 95909c2a.