fix(settings): Make sure there's a fallback for users without access to the google play store
Because: - Some users might not have the play store installed. - These users would get a spinner if they tried the pair flow with a non firefox default browser. This Commit: - Adds a fallback if the play store doesn't open. - Let's user click the 'Download Firefox' button as a fallback. Note, if users can't access the play store, then the download link doesn't work, users will should be accustomed to the playstore not working and be able to find a work around.