Follow-up properties setting for deployment ID and API key in a single dialog

[daenamkim]

Follow-up: #24 (comment), #23 (comment)

For convenience, unify deployment ID and API key properties into a single dialog but there are some issues:

Issues

• Need to add another permission scope: https://www.googleapis.com/auth/script.container.ui it seems not related to our add-on features.
  

• Custom HTML template not imported but hard coded works (I might have done wrong)

• Style consistency that standard dialog has styles (font, title, message, button, close) but a custom template needs styles. i.e.