res_pjsip: Add TEL URI support for basic calls.

res_pjsip: Add TEL URI support for basic calls.

This change allows TEL URI requests to come through for basic calls. The
allowed requests are INVITE, ACK, BYE, and CANCEL. The From and To
headers will now allow TEL URIs, as well as the request URI.

Support is only for TEL URIs present in traffic from a remote party.
Asterisk does not generate any TEL URIs on its own.

ASTERISK-26894

Change-Id: If5729e6cd583be7acf666373bf9f1b9d653ec29a