RFR: 8261513: Various BasicConstraintsExtension issues

[Ben Perez]

8261513: Various BasicConstraintsExtension issues

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Commit messages:
 - Changed constructor, getPathLen, and toString to return a canonical representation for unconstrained pathLens

Changes: https://git.openjdk.org/jdk/pull/20224/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20224&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8261513
  Stats: 7 lines in 1 file changed: 0 ins; 2 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/20224.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20224/head:pull/20224

PR: https://git.openjdk.org/jdk/pull/20224