res_pjsip_config_wizard: Add 2 new parameters to help with proxy config

Two new parameters have been added to the pjsip config wizard.

 * Setting 'sends_line_with_registrations' to true will cause the wizard
   to skip the creation of an identify object to match incoming request
   to the endpoint and instead add the line and endpoint parameters to
   the outbound registration object.

 * Setting 'outbound_proxy' is a shortcut for adding individual
   endpoint/outbound_proxy, aor/outbound_proxy and
   registration/outbound_proxy parameters.

Change-Id: I678e5f80765734c056620528a6d40d82736ceeb0