RFR: JMC-7158: [JFR Writer] Improve single-value types handling

[Jaroslav Bachorik]

JMC-7158: [JFR Writer] Improve single-value types handling

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Commit messages:
 - JMC-7158: [JFR Writer] Improve single-value types handling

Changes: https://git.openjdk.java.net/jmc/pull/224/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmc&pr=224&range=00
  Issue: https://bugs.openjdk.java.net/browse/JMC-7158
  Stats: 80 lines in 7 files changed: 44 ins; 13 del; 23 mod
  Patch: https://git.openjdk.java.net/jmc/pull/224.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/224/head:pull/224

PR: https://git.openjdk.java.net/jmc/pull/224