RFR: 8469: Should make rules and page heading accessible through keyboard in JFR overview page

[Aymane Harmaz]

This PR makes it possible to reach JFR result pages and expand / collapse rule text on the JFR result overview using keyboard enter and tab keys.

<img width="1067" height="480" alt="focused-rule" src="https://github.com/user-attachments/assets/df38672e-4882-420a-8e45-f7f3f33349cd" />

<img width="1067" height="480" alt="expanded-rule-using-enter-key" src="https://github.com/user-attachments/assets/ec45e75b-48f6-424b-a8e7-7bc5b34bae0e" />

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Commit messages:
 - 8469: Should make rules and page heading accessible through keyboard in JFR overview page

Changes: https://git.openjdk.org/jmc/pull/683/files
  Webrev: https://webrevs.openjdk.org/?repo=jmc&pr=683&range=00
  Issue: https://bugs.openjdk.org/browse/JMC-8469
  Stats: 17 lines in 3 files changed: 15 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jmc/pull/683.diff
  Fetch: git fetch https://git.openjdk.org/jmc.git pull/683/head:pull/683

PR: https://git.openjdk.org/jmc/pull/683