- Adds a download button in the user menu
# Important Notes
- The "upgrade to" button will be absent when the user already has a plan, as the only place where an "upgrade to" button shows up is the cloud view, when the user's account has not yet been enabled.
- The upgrade button currently links to https://enso.org/pricing - which does not yet exist. This is intentional, as another PR would be required to switch the URL, if we were to initially point to the one at https://enso-org.github.io.
- The pricing page would still not work, as that requires payment functionality, which is not yet complete
