RFR: JDK-8263261 Extend String::translateEscapes to support unicode escapes [v14]

[Jim Laskey]

> Currently String::translateEscapes does not support unicode escapes, reported as a IllegalArgumentException("Invalid escape sequence: ..."). String::translateEscapes should translate unicode escape sequences to provide full coverage,

Jim Laskey has updated the pull request incrementally with two additional commits since the last revision:

 - Update test/jdk/java/lang/String/TranslateEscapes.java
   
   Co-authored-by: ExE Boss <3889017+ExE-Boss at users.noreply.github.com>
 - Update src/java.base/share/classes/java/lang/String.java
   
   Co-authored-by: ExE Boss <3889017+ExE-Boss at users.noreply.github.com>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/17491/files
  - new: https://git.openjdk.org/jdk/pull/17491/files/74707a66..61a3abab

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17491&range=13
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17491&range=12-13

  Stats: 8 lines in 2 files changed: 0 ins; 7 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/17491.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17491/head:pull/17491

PR: https://git.openjdk.org/jdk/pull/17491