res_pjsip_path.c: Fix path when dialing using PJSIP_DIAL_CONTACTS()

res_pjsip_path.c: Fix path when dialing using PJSIP_DIAL_CONTACTS()

When using the PJSIP_DIAL_CONTACTS() function for use in the Dial()
command, the contacts are returned in text form, so the input to
the path_outgoing_request() function is a contact value of NULL.
The issue was reported in ASTERISK-28211, but was not actually fixed
in ASTERISK-30100. This fix brings back the code that was previously
removed and adds code to search for a contact to extract the path
value from it.

(cherry picked from commit caa1820d2bb643ec9e891d082d9f6f1a85b05108)