RFR: 8343412: Missing escapes for single quote marks in javac.properties

[Archie Cobbs]

Please review these simple syntax fixes for `javac.properties`.

The source file `javac.properties` contains the English message bundle for the javac tool. Since the strings in this file are `MessageFormat` format strings, any single quotes must be escaped by doubling them.

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Commit messages:
 - Include javac.properties in the MessageFormat validation check.
 - Fix unescaped single quotes in javac.properties.

Changes: https://git.openjdk.org/jdk/pull/21816/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21816&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8343412
  Stats: 6 lines in 2 files changed: 0 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/21816.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21816/head:pull/21816

PR: https://git.openjdk.org/jdk/pull/21816