[jdk17u] RFR: 8268457: XML Transformer outputs Unicode supplementary character incorrectly to HTML

[Alex Kasko]

Clean backport of an XSL fix.

Note, included test is broken, it was fixed with [JDK-8274606](https://bugs.openjdk.java.net/browse/JDK-8274606), I intend to follow up with its backport.

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Commit messages:
 - Backport 83bce94cc8a7fb45b0604598411fbecc62000dfd

Changes: https://git.openjdk.java.net/jdk17u/pull/162/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17u&pr=162&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268457
  Stats: 194 lines in 7 files changed: 168 ins; 21 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk17u/pull/162.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17u pull/162/head:pull/162

PR: https://git.openjdk.java.net/jdk17u/pull/162