[mod_spandsp] Fix compilation against >=2023/06/02 spandsp

[mod_spandsp] Fix compilation against >=2023/06/02 spandsp

* [mod_spandsp] Fix compilation against >=2023/06/02 spandsp

spandsp, beginning with commit d9681c37 and coinciding with the
SPANDSP_RELEASE_DATE of 20230620, introduced the following changes to
its V.18 protocol API, which FreeSWITCH is not able to compile against:
- Certain V.18 constants were renamed.
- The v18_init function now requires passing a third function, handling
the V.18 modem's status changes.

This patch allows FreeSWITCH to build against current versions of
spandsp by:
- Using the new V.18 constant names.
- Implementing a simple status reporter callback function and passing it
as the third function to v18_init.

Additionally, it retains backward compatibility with prior versions of
spandp through #if conditions checking the value of
SPANDSP_RELEASE_DATE.

Signed-off-by: Patrice Fournier <patrice.fournier@t38fax.com>
* [mod_spandsp] Pass session to handle_v18_status.

---------

Signed-off-by: Patrice Fournier <patrice.fournier@t38fax.com>
Co-authored-by: Morgan Scarafiotti <morgan.scarafiotti@t38fax.com>
Co-authored-by: Andrey Volk <andywolk@gmail.com>