<AWT Dev> RFR: 8251123: doclint warnings about missing javadoc tags and comments

[Sergey Bylokhov]

We have a number of missing javadoc tags and comments in the desktop module.
Most of the missing comments are related to the serialized form.

The fix:
  - Adds missing comments to the non-static/non-transient fields(even private) of the "serializable" classes
  - Adds comments to the "serializable" classes even if those classes are non-public
  - Fixes references/adds missing tags to the special methods(like readObject/writeObject)
  - Delete the java.awt.PeerFixer class.

I need advice about what exact change should be reviewed in  the CSR(except PeerFixer removal)

Note that in some cases I added the comments to the "implementation details", so I did not specify it fully.

The old review request:
https://mail.openjdk.java.net/pipermail/beans-dev/2020-August/000423.html

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Commit messages:
 - 8251123: doclint warnings about missing javadoc tags and comments

Changes: https://git.openjdk.java.net/jdk/pull/369/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=369&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8251123
  Stats: 1306 lines in 69 files changed: 810 ins; 214 del; 282 mod
  Patch: https://git.openjdk.java.net/jdk/pull/369.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/369/head:pull/369

PR: https://git.openjdk.java.net/jdk/pull/369