<AWT Dev> RFR: 8211958: Broken links in java.desktop files

[Sergey Bylokhov]

Most of the broken links were fixed already by the JDK-8225368 and JDK-8214817
This change fix just a few.

Also two cleanups are applied:
 - The `../../java/awt/doc-files/` in some cases simplified to `doc-files/`
 - The html links to the java classes via `<a href>` replaced by the `{@link }`

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Commit messages:
 - Initial fix

Changes: https://git.openjdk.java.net/jdk/pull/998/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=998&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8211958
  Stats: 43 lines in 9 files changed: 0 ins; 4 del; 39 mod
  Patch: https://git.openjdk.java.net/jdk/pull/998.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/998/head:pull/998

PR: https://git.openjdk.java.net/jdk/pull/998