RFR: JMC-7090: [JFR Writer] Make constant pool optional when registering a new type [v5]

[Jaroslav Bachorik]

> JMC-7090: [JFR Writer] Make constant pool optional when registering a new type

Jaroslav Bachorik has updated the pull request incrementally with two additional commits since the last revision:

 - Use constant pool refs only for types with associated constant pool
 - Update copyright

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Changes:
  - all: https://git.openjdk.java.net/jmc/pull/200/files
  - new: https://git.openjdk.java.net/jmc/pull/200/files/ce9d4197..51581133

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jmc&pr=200&range=04
 - incr: https://webrevs.openjdk.java.net/?repo=jmc&pr=200&range=03-04

  Stats: 10 lines in 2 files changed: 3 ins; 0 del; 7 mod
  Patch: https://git.openjdk.java.net/jmc/pull/200.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/200/head:pull/200

PR: https://git.openjdk.java.net/jmc/pull/200