Add options to Contact Permission Prompt

[danry25]

It would be good to give users the choice of importing the system contact list, or using just the contacts provided in the config file.

Perhaps we could reword this prompt to ask "Do you want to import your contacts? If so, authorize the Accelerate Networks App under Settings > Privacy > Contacts"

Change Continue into 2 buttons "No" or "Import Contacts", the latter of which does the same navigation to the Contacts permission.

Additionally, we need to expand this logic to generate the contact list including all existing extensions on a domain, the same as what we do for Yealink phonebooks currently.