When we don't detect an SDK, we prompt to install Flutter and try to locate Git.

Sometimes we fail to find Git (perhaps it's not installed, or not on PATH, or VS Code/Windows was not restarted since it was added to PATH).

Rather than just sending these users to the website (which now tries to send them back through the same flow they may have just tried), we should first try harder to find Git. For example we could:

• Look in the default install locations automatically (even if not on PATH)
• See if we can use the built-in Git extension to clone or get the Git path (is this a Git path?)
• Make it clearer to the user that we failed to find Git (instead of silently going to the website)