Implement a BFDTrapObserver

[lunkwill42]

Scope and purpose

Fixes #292. Dependent on #303 to be merged first.

bfdSessUp and bfdSessDown traps only tell which BFD sessions have changed state and why, but does not actually include the new state value for the session. This means most of this new observer's work is to just offload everything to BFDTask to poll the individual session(s) that have changed state and ensure state and events are updated accordingly.

This pull request

• Adds a new BFD Trap observer to the default Zino trap listener setup.
• Adds the optional ability for the existing BFDTask to fetch and update single BFD sessions, used by the trap observer.

Contributor Checklist

Every pull request should have this checklist filled out, no matter how small it is.
More information about contributing to Zino can be found in the
README.

• Added a changelog fragment for towncrier
• Added/amended tests for new/changed code
• Added/changed documentation
• Linted/formatted the code with black, ruff and isort, easiest by using pre-commit
• The first line of the commit message continues the sentence "If applied, this commit will ...", starts with a capital letter, does not end with punctuation and is 50 characters or less long. See https://cbea.ms/git-commit/

[github-actions]

🦙 MegaLinter status: ✅ SUCCESS

Descriptor	Linter	Files	Fixed	Errors	Elapsed time
✅ PYTHON	black	86		0	1.43s
✅ PYTHON	isort	86		0	0.31s
✅ PYTHON	ruff	86		0	0.03s

See detailed report in MegaLinter reports

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[github-actions]

Test results

    3 files      3 suites   1m 15s ⏱️
  432 tests   432 ✅ 0 💤 0 ❌
1 296 runs  1 294 ✅ 2 💤 0 ❌

Results for commit ec71030.

♻️ This comment has been updated with latest results.

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[codecov]

Codecov Report

Attention: Patch coverage is 98.11321% with 1 line in your changes missing coverage. Please review.

Project coverage is 98.69%. Comparing base (a75b0e8) to head (ec71030).

Files	Patch %	Lines
src/zino/tasks/bfdtask.py	94.74%	1 Missing ⚠️

Additional details and impacted files

@@                           Coverage Diff                            @@
##           feature/snmp-get2-multiple-variables     #305      +/-   ##
========================================================================
- Coverage                                 98.70%   98.69%   -0.01%     
========================================================================
  Files                                        53       54       +1     
  Lines                                      7055     7100      +45     
========================================================================
+ Hits                                       6963     7007      +44     
- Misses                                       92       93       +1     

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[johannaengland]

But I would like to have an updated news fragment - act is a strange choice here. IMO it makes more sense to simply remove Act to from it.

[lunkwill42]

But I would like to have an updated news fragment - act is a strange choice here. IMO it makes more sense to simply remove Act to from it.

As release manager I'm still responsible for editing the final changelog, so I'll just keep that in mind when the time comes :) Thank you!