Implement XEP-0167: Jingle RTP Sessions SRTP negotiation

[melvo]

PR check list:

• [x] Document your code
• [x] Add \since QXmpp 1.X, QXMPP_EXPORT
• [x] Fix doxygen warnings (see log when building with -DBUILD_DOCUMENTATION=ON)
• [x] Update doc/doap.xml
• [x] Add unit tests
• [x] Format the code: Run clang-format -i src/<edited-file(s)> tests/<edited-file(s)>

[codecov[bot]]

Codecov Report

Base: 68.51% // Head: 68.47% // Decreases project coverage by -0.03% :warning:

Coverage data is based on head (35a3ce7) compared to base (0cd975e). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #487 +/- ## ========================================== - Coverage 68.51% 68.47% -0.04% ========================================== Files 294 292 -2 Lines 25340 25653 +313 ========================================== + Hits 17361 17567 +206 - Misses 7979 8086 +107 ``` | [Impacted Files](https://codecov.io/gh/qxmpp-project/qxmpp/pull/487?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qxmpp-project) | Coverage Δ | | |---|---|---| | [src/base/QXmppJingleIq.cpp](https://codecov.io/gh/qxmpp-project/qxmpp/pull/487/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qxmpp-project#diff-c3JjL2Jhc2UvUVhtcHBKaW5nbGVJcS5jcHA=) | `90.62% <100.00%> (+1.11%)` | :arrow_up: | | [src/base/QXmppJingleIq.h](https://codecov.io/gh/qxmpp-project/qxmpp/pull/487/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qxmpp-project#diff-c3JjL2Jhc2UvUVhtcHBKaW5nbGVJcS5o) | `100.00% <100.00%> (ø)` | | | [tests/qxmppjingleiq/tst\_qxmppjingleiq.cpp](https://codecov.io/gh/qxmpp-project/qxmpp/pull/487/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qxmpp-project#diff-dGVzdHMvcXhtcHBqaW5nbGVpcS90c3RfcXhtcHBqaW5nbGVpcS5jcHA=) | `100.00% <100.00%> (ø)` | | | [src/base/QXmppFutureUtils\_p.h](https://codecov.io/gh/qxmpp-project/qxmpp/pull/487/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qxmpp-project#diff-c3JjL2Jhc2UvUVhtcHBGdXR1cmVVdGlsc19wLmg=) | `72.41% <0.00%> (-6.84%)` | :arrow_down: | | [src/base/QXmppError.h](https://codecov.io/gh/qxmpp-project/qxmpp/pull/487/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qxmpp-project#diff-c3JjL2Jhc2UvUVhtcHBFcnJvci5o) | `0.00% <0.00%> (ø)` | | | [src/base/QXmppError.cpp](https://codecov.io/gh/qxmpp-project/qxmpp/pull/487/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qxmpp-project#diff-c3JjL2Jhc2UvUVhtcHBFcnJvci5jcHA=) | `0.00% <0.00%> (ø)` | | | [src/client/QXmppFileSharingManager.h](https://codecov.io/gh/qxmpp-project/qxmpp/pull/487/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qxmpp-project#diff-c3JjL2NsaWVudC9RWG1wcEZpbGVTaGFyaW5nTWFuYWdlci5o) | `0.00% <0.00%> (ø)` | | | [src/client/QXmppFileSharingProvider.h](https://codecov.io/gh/qxmpp-project/qxmpp/pull/487/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qxmpp-project#diff-c3JjL2NsaWVudC9RWG1wcEZpbGVTaGFyaW5nUHJvdmlkZXIuaA==) | `0.00% <0.00%> (ø)` | | | [src/client/QXmppFileSharingManager.cpp](https://codecov.io/gh/qxmpp-project/qxmpp/pull/487/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qxmpp-project#diff-c3JjL2NsaWVudC9RWG1wcEZpbGVTaGFyaW5nTWFuYWdlci5jcHA=) | `0.00% <0.00%> (ø)` | | | ... and [11 more](https://codecov.io/gh/qxmpp-project/qxmpp/pull/487/diff?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qxmpp-project) | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qxmpp-project). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qxmpp-project)

:umbrella: View full report at Codecov.
:loudspeaker: Do you have feedback about the report comment? Let us know in this issue.