Support "no signature" signers on local X.509 certificates.

[JonathanLennox]

As defined in draft-davidben-x509-alg-none RFC 9925.

[codecov]

Codecov Report

❌ Patch coverage is 81.81818% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 47.90%. Comparing base (6708140) to head (1cfd0cd).

Files with missing lines	Patch %	Lines
...rm/src/main/kotlin/org/jitsi/nlj/dtls/DtlsUtils.kt	33.33%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #2260      +/-   ##
============================================
+ Coverage     47.88%   47.90%   +0.01%     
- Complexity     2715     2721       +6     
============================================
  Files           381      382       +1     
  Lines         22174    22184      +10     
  Branches       3367     3368       +1     
============================================
+ Hits          10619    10627       +8     
- Misses        10400    10401       +1     
- Partials       1155     1156       +1     

Files with missing lines	Coverage Δ
...ain/kotlin/org/jitsi/nlj/dtls/AlgUnsignedSigner.kt	100.00% <100.00%> (ø)
...m/src/main/kotlin/org/jitsi/nlj/dtls/DtlsConfig.kt	96.77% <100.00%> (+0.22%)	⬆️
...rm/src/main/kotlin/org/jitsi/nlj/dtls/DtlsUtils.kt	55.93% <33.33%> (-0.97%)	⬇️

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6708140...1cfd0cd. Read the comment docs.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[JonathanLennox]

Now defined in RFC 9925, marking PR as ready.