RFR: 8296787: Unify debug printing format of X.509 cert serial numbers [v3]

[Ben Perez]

> Updated `X509CertSelector.java` and `SerialNumber.java` to use same debug printing format for X.509 serial numbers. The format in `SSLLogger.java` is slightly different but now uses the `toString` method in `SerialNumber.java` for better readability.

Ben Perez has updated the pull request incrementally with one additional commit since the last revision:

  Changed serial number formatting method

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Changes:
  - all: https://git.openjdk.org/jdk/pull/16834/files
  - new: https://git.openjdk.org/jdk/pull/16834/files/fc6ebd21..1783ea3a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16834&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16834&range=01-02

  Stats: 7 lines in 3 files changed: 2 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/16834.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16834/head:pull/16834

PR: https://git.openjdk.org/jdk/pull/16834