Additional "nice to haves" for setting up piplines

[wadewegner]

1. On enable/disable of autodeploy or autodestroy, provide an updated message to the user telling them exactly what we're doing. (@raulb's suggestion)

2. Create a heroku pipelines:disconnect -p "pipeline" command. (@bigkevmcd's suggestion)

3. Handle the following scenario better (I think this is due to the repo already being connected to a pipeline, but not sure why we get this kind of error, @bigkevmcd ):

$ heroku pipelines:connect "my-pipeline" -r "bigkevmcd/my-repo"
Linking to repo... !
 ▸    Response code 422 (Unprocessable Entity)

4. For reviewapps:disable perhaps the help should say that if no options are provided, it will disable both (@bigkevmcd's suggestion)?

5. The pattern from reviewapps:enable might be adopted where it outputs how it's interpreting the flags (@bigkevmcd's suggestion)?

if (context.flags.autodeploy) {
  cli.log('Disabling auto deployment...');
  settings.pull_requests.auto_deploy = false;
}

6. Maybe reviewapps:enable should indicate after how many days the app will be autodestroyed?