Add HEPv3 support to siptrace

[giavac]

This PR allows kamailio to duplicate messages to Homer using HEPv3 [0].
An optional correlation ID (which can contain PVs) can be passed to sip_trace().

The packing macros in hep.h are authored by @camilleoudot and I've just used them.

An example of formats:

modparam("siptrace", "duplicate_uri", "sip:127.0.0.1:9062")
...
sip_trace("sip:127.0.0.1:9060", "123"); // duplicate URI + correlation ID
sip_trace("", "345"); // default URI + correlation ID
sip_trace("", "$fU-678"); // default URI + correlation ID with PVs
sip_trace(); // default URI + no correlation ID

[0] https://github.com/sipcapture/HEP/blob/master/docs/HEP3_rev12.pdf

[miconda]

Thanks! Can be merged and backported to branch 5.0 as it fixes the compatibility with HEPv3.

Note: I invited @giavac to join developers team, given his many contributions over the time

[giavac]

Thanks Daniel

[miconda]

@giavac welcome, thanks for all your contributions! Now you should be able to merge the PR by yourself and commit directly (if you want that instead of PR -- that should be more handy for backports at least).

[giavac]

I'll leave some time for @adubovikov to read/review, then I'll proceed with merge and backport.

[adubovikov]

looks very good for me!