RFR: 8354968: Replace unicode sequences in comment text with UTF-8 characters

[Magnus Ihse Bursie]

As part of the UTF-8 cleaning up done in [JDK-8301971](https://bugs.openjdk.org/browse/JDK-8301971), I looked at where and how we are using unicode sequences (`\uXXXX`). In several string literals, I think the unicode sequences still has merit, if they improve clarity or readability of the code. Some instances are more gray zone. But the places where it does not make sense at all are in comments, as part of fluid text comments. There they are just disruptive and not helpful at all. I tried to locate all such places (but I might have missed places, I did not do a proper lexical analysis to find comments) and fix them.

99% of this fix is to turn poor `Peter von der Ah\u00e9` into `Peter von der Ahé`. 😆 

I checked some random samples on when this was introduced to see if there were some particular commit that mistreated the encoding, but they have been there since the original release of the open JDK source code.

There are likely many more places where direct UTF-8 encoded characters is preferable to unicode sequences, but this seemed like a safe and trivial first start.

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Commit messages:
 - 8354968: Replace unicode sequences in comment text with UTF-8 characters

Changes: https://git.openjdk.org/jdk/pull/24727/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24727&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8354968
  Stats: 158 lines in 153 files changed: 0 ins; 2 del; 156 mod
  Patch: https://git.openjdk.org/jdk/pull/24727.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24727/head:pull/24727

PR: https://git.openjdk.org/jdk/pull/24727