RFR: 8317374: Add Let's Encrypt ISRG Root X2

[Rajan Halade]

This PR is to add new TLS root certificates from Let's Encrypt. This CA has gone through https://www.oracle.com/java/technologies/javase/carootcertsprogram.html process.


The release-note is at [JDK-8318618](https://bugs.openjdk.org/browse/JDK-8318618)

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Commit messages:
 - 8317374: Add Let's Encrypt ISRG Root X2

Changes: https://git.openjdk.org/jdk/pull/16455/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16455&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8317374
  Stats: 39 lines in 3 files changed: 35 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/16455.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16455/head:pull/16455

PR: https://git.openjdk.org/jdk/pull/16455