RFR: 8296787: Unify debug printing format of X.509 cert serial numbers [v2]

[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 debug format to separate bytes with a colon

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Changes:
  - all: https://git.openjdk.org/jdk/pull/16834/files
  - new: https://git.openjdk.org/jdk/pull/16834/files/0d5550ef..fc6ebd21

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16834&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16834&range=00-01

  Stats: 5 lines in 2 files changed: 1 ins; 0 del; 4 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