sip: add RFC 3262 support

[maximilianfridrich]

Adds tests for RFC 3262.

Related:

• sip: add RFC 3262 support re#419

[cspiel1]

I renamed this PR. It needs to have the same name like the re PR.

[sreimers]

The new tests test_sipsess_100rel_caller_require and test_sipsess_100rel_supported are very slow:

$ time ./retest -r -v test_sipsess_100rel_supported     
single testcase: test_sipsess_100rel_supported
retest: libre version 2.5.0 (x86_64/linux)
using async polling method 'epoll'
using datapath './data'
regular tests:       OK
./retest -r -v test_sipsess_100rel_supported  0,00s user 0,00s system 0% cpu 10,009 total

Looks like they run into the re_main timeout override limit, maybe a re_cancel is missing.
@cspiel1 @maximilianfridrich

[maximilianfridrich]

The new tests test_sipsess_100rel_caller_require and test_sipsess_100rel_supported are very slow:

I will look into this shortly.

[maximilianfridrich]

Fixed in:

• sipsess: fix 100rel test performance #90