Re-land:  Allow users to pass in Xcode build settings as env variables to flutter build macos FLUTTER_XCODE_  (#82298)

Revert "Allow users to pass in Xcode build settings as env variables to flutter build macos FLUTTER_XCODE_ (#81384)" (#82004)

This reverts commit 0bba935b.

Allow users to pass in Xcode build settings as env variables to flutter build macos FLUTTER_XCODE_ (#81384)

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

* opt out the flutter tool

* oops EOF

* fix import

* Update tool_backend.dart

* Update daemon_client.dart

* fix more

* Add text to --analyze-size command output to launch DevTools with size data.

This reverts commit 0b6b3eec.

This reverts commit 70f8fdee.