Add support for ietf-syslog.yang

[troglobit]

Description

WIP (more coming soon ...)

REMEMBER: rebase/update commit message for CLI hang fix!

Checklist

Tick relevant boxes, this PR is-a or has-a:

• [ ] Bugfix
  • [ ] Regression tests
  • [ ] ChangeLog updates (for next release)
• [X] Feature
  • [X] YANG model change => revision updated?
  • [X] Regression tests added?
  • [ ] ChangeLog updates (for next release)
  • [ ] Documentation added?
• [ ] Code style update (formatting, renaming)
• [X] Refactoring (please detail in commit messages)
• [ ] Build related changes
• [ ] Documentation content changes
• [ ] Other (please describe):

[troglobit]

Marking this as draft to make it clear it's not done yet.

TODO

Currently the last patch, to add support for audit, does not report the correct user initiating the change. APIs tested include sr_session_get_user() and sr_nacm_get_user(). Both return root, so this needs to be investigated further.

• [x] Investigate user change tracking in sysrepo, netopeer2, rousette, and klishd

[troglobit]

Finally done.