res/res_pjsip_dlg_options: Add a module to handle in-dialog OPTIONS requests

res/res_pjsip_dlg_options: Add a module to handle in-dialog OPTIONS requests

This patch adds a new session supplement that handles in-dialog OPTIONS
requests. Said OPTIONS requests are sent a 200 OK, as an endpoint lookup
for the OPTIONS request would already have been done by the time the
session supplement receives the inbound request.

ASTERISK-24862 #close
Reported by: yaron nahum
patches:
  res_pjsip_dlg_options.c submitted by yaron nahum (License 6676)

Change-Id: Iefc901a7c5c88d9d4b853188f85092d9eb7b6ada