RFR: 6928542: Chinese characters in RTF are not decoded

[Ichiroh Takiguchi]

"character set of font" (font charset) table was created by "Rich Text Format Specification 1.9.1"
https://interoperability.blob.core.windows.net/files/Archive_References/[MSFT-RTF].pdf
It refers windgi.h
https://learn.microsoft.com/en-us/windows/win32/api/wingdi/ns-wingdi-textmetrica

Test files and testcase are in bugid [JDK-6928542](https://bugs.openjdk.org/browse/JDK-6928542)

Additional change:
Special character `\line` should `\n`

**Note:** Following GitHub actions were failed
linux-x86 / test (jdk/tier1 part 1) was failed, it seems it was already reported
> [JDK-8305875](https://bugs.openjdk.org/browse/JDK-8305875) Test TraceVirtualThreadLocals should be run with continuations only

windows-aarch64 / build (debug) was failed, but I have no idea...

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Commit messages:
 - 6928542: Chinese characters in RTF are not decoded

Changes: https://git.openjdk.org/jdk/pull/13553/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13553&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-6928542
  Stats: 264 lines in 3 files changed: 261 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/13553.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13553/head:pull/13553

PR: https://git.openjdk.org/jdk/pull/13553