modules/sca: optionally update call-info state for only caller or callee.

- sca_call_info_update can now take an int argument (1=caller, 2=callee)
  limiting call-info state update to only that leg's AoR.
modules/sca: use sca_create_canonical_aor in INVITE/2OO OK handler.

- abstract AoR construction for future improvements.