[jfx17u] RFR: 8306329: Update ICU4C to 73.1

[Johan Vos]

Clean backport of
8306329: Update ICU4C to 73.1
Reviewed-by: kcr, jvos

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Commit messages:
 - 8306329: Update ICU4C to 73.1

Changes: https://git.openjdk.org/jfx17u/pull/145/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx17u&pr=145&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306329
  Stats: 35622 lines in 738 files changed: 9131 ins; 2562 del; 23929 mod
  Patch: https://git.openjdk.org/jfx17u/pull/145.diff
  Fetch: git fetch https://git.openjdk.org/jfx17u.git pull/145/head:pull/145

PR: https://git.openjdk.org/jfx17u/pull/145