Describe the bug
I'm working with the win32 package (https://github.com/timsneath/win32) and I want to be able to easily flip between 32-bit and 64-bit SDKs to test my code. Unfortunately, the version switcher isn't available because there is one example buried deep in the folder structure that happens to use Flutter :(
I have my SDK folder set up, and other Dart-only projects provide configuration for switching:

To Reproduce
Steps to reproduce the behavior:
- git clone the project above
- Run it from a machine with multiple Dart SDKs
Expected behavior
Don't know what the right solution is here. I should be able to trigger the chooser somehow though. The presence of a Flutter folder shouldn't cause the entire Dart project to be unable to use a Dart SDK.
Versions (please complete the following information):
- VS Code version: 1.51.1 (user setup)
- Dart extension version: 3.16.0
- Dart/Flutter SDK version: multiple
