Resolve incoming trap varbinds properly

[lunkwill42]

Scope and purpose

The varbinds of an incoming trap message were incorrectly resolved (most likely due to a misunderstanding of PySNMP complexity).

In fact, the original resolver only resolved the name of the incoming variable, but the subtype of the value also needs to be resolved according to the MIB definition of the incoming variable.

This new resolver ensures the value is also resolved to the correct type. An example: The incoming raw value may be an ASN1 OctetString, but seen in light of the resolved MIB object name, it might actually be resolved as a InetAddress textual convention type instead (which would heavily influence how the incoming value is parsed to a Python value).

This issue was discovered during implementation of #288 as incoming BGP operational state values were not translated to names, but stayed as opaque integers

This pull request

• changes the internal implementation of the trap varbind resolver, but no external usage is affected (except for improved ability to resolve incoming value types according to MIBs)

Contributor Checklist

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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/
• If applicable: Created new issues if this PR does not fix the issue completely/there is further work to be done

[github-actions]

🦙 MegaLinter status: ✅ SUCCESS

Descriptor	Linter	Files	Fixed	Errors	Elapsed time
✅ PYTHON	black	6		0	0.6s
✅ PYTHON	isort	6		0	0.26s
✅ PYTHON	ruff	6		0	0.01s

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[github-actions]

Test results

    3 files      3 suites   59s ⏱️
  416 tests   416 ✅ 0 💤 0 ❌
1 248 runs  1 246 ✅ 2 💤 0 ❌

Results for commit 42cbb27.

♻️ This comment has been updated with latest results.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.90%. Comparing base (cfef3d8) to head (42cbb27).
Report is 11 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #290      +/-   ##
==========================================
+ Coverage   98.89%   98.90%   +0.01%     
==========================================
  Files          51       52       +1     
  Lines        6912     6972      +60     
==========================================
+ Hits         6835     6895      +60     
  Misses         77       77              

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[sonarcloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

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

See analysis details on SonarCloud

[lunkwill42]

No comments received in an IRL code review within our team, so I'm merging this now.