Add Jingle: XEP-0166, XEP-0234, XEP-0261, XEP-0047

[H3rnand3zzz]

Yet to be finished, the plan* is to

• [x] Pass autotests on the Github.
• [ ] Complete all TODOs
• [ ] Improve stability (e.g. file permissions etc. validation, handle errors on write)
• [ ] Add autocomplete
• [ ] Improve security (file name, size validation etc.)
• [ ] Detect and fix mem leaks with the Valgrind
• [ ] Add at least some autotests
• [ ] Code Review by the Profanity team
• [ ] Release

*The plan is not final, it might change.

How to test the functionality

/help jingle

I ran valgrind when using my new feature

planned

Fix #1871 (rather implement, but github understands only fix to link the PR as a potential solution for the issue).