flutter_tool: DeferredComponent and LoadingUnit classes, Manifest deferred-components parsing (#75394)

This reverts commit 8b6baae4.

Our current top crasher is an unclear error when ProcessManager fails to resolve an executable path. To fix this, we'd like to being adjusting the process resolution logic and adding more instrumentation to track failures. In order to begin the process, the ProcessManager has been folded back into the flutter tool

= gets escaped into %3D which seems to be tripping up cmake on windows since % is a control character. Switch to base64 encoding, since this does not have % nor , in the output character set.

This change is not trivially cherry pickable, and isn't tested on windows aside from my local, manual tests due to the planned CI work not being complete yet.

Fixes #75017
Fixes #74705

* opt out the flutter tool

* oops EOF

* fix import

* Update tool_backend.dart

* Update daemon_client.dart

* fix more

* Reorganize files

* Use l10n.yaml instead of command line args

In principle this is backwards compatible; I just merged all the classes into one and deprecated everything that became redundant as a result.

This reverts commit 8749d955.

In principle this is backwards compatible; I just merged all the classes into one and deprecated everything that became redundant as a result.

[flutter_tools] remove most globals from asset system and remove Cache manipulation in unit tests (#70011)

Fixes #69416
Fixes #70121

Instead of loading the use-material-design asset data from a yaml file in the repo, leave it in dart code and simplify. Remove some of the globals, but not enough to update to testWithoutContext

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.

There have been some more additional reports of a missing 'package:characters' import after upgrading flutter. This has me concerned that our pub caching logic is incorrect. Instead of the tool attempting to guess when pub should be run, always delegate to pub.

Also takes an opportunity to fix the kernel snapshot depending on the .packages or package_config. Due to the generated: date field this causes extra rebuilds. Instead when pub get is run, write out an additional file with just the package contents and version.

Fixes #66777
Fixes #65723

Revert "[flutter_tools] refactor drive launch into separate service, split by mobile+desktop and web (#68451)" (#68845)

This reverts commit 2e75f52a.

[flutter_tools] refactor drive launch into separate service, split by mobile+desktop and web (#68451)

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.

* Generate pubspec.yaml for synthetic package if it did not exist prior