[jdk21u] RFR: 8294158: HTML formatting for PassFailJFrame instructions

[Alexey Ivanov]

Backporting an enhancement that adds HTML formatting for the test instructions in PassFailJFrame which is a manual test framework.

Clean backport. Low risk.

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Commit messages:
 - Backport 14090ef6039ff2f3064f397a75219b2bc715cc27

Changes: https://git.openjdk.org/jdk21u/pull/352/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u&pr=352&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8294158
  Stats: 40 lines in 1 file changed: 35 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk21u/pull/352.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u.git pull/352/head:pull/352

PR: https://git.openjdk.org/jdk21u/pull/352