Support installing the devtunnel CLI from the dashboard notification

The dev tunnels hosting integration currently checks if the needed devtunnel CLI is installed and if not shows a notification on the dashboard pointing users to the installation instructions. Unfortunately though, even if the user clicks the link and follows the instructions to install the CLI, the shell that launched the AppHost and dashboard must be restarted before it can be detected, as the CLI installer will be launched from a separate shell instance.

We should consider whether offering a direct install button on the notification that launches the appropriate installer from the AppHost can result in an experience where the user can get prompted to install the CLI, clicks the prompt to do the install, and then the resource can continue starting without the user having to close the AppHost and the shell session they launched it from for the CLI install to be detected. This would result in a much smoother and delightful experience.

The devtunnel CLI supports the [following installers](https://learn.microsoft.com/azure/developer/dev-tunnels/get-started?tabs=windows#install) that update the PATH:

- Windows: winget (`winget install Microsoft.devtunnel`)
- macOS: Homebrew (`brew install --cask devtunnel`)
- macOS/Linux: bash install script (`curl -sL https://aka.ms/DevTunnelCliInstall | bash`)