RFR: 8267708: Remove references to com.sun.tools.javadoc.**

[Pavel Rappo]

Although the `com.sun.tools.javadoc.**` packages were removed in JDK-8215584, some references to them remain, mainly in the form of links in doc comments. Some of those links refer to classes that never existed, which I reckon is due to a typo; for example, this reference

    com.sun.tools.javadoc.ClassDocImpl#findField

should've looked like this

    com.sun.tools.javadoc.main.ClassDocImpl#findField

Grep showed that some tests also use `com.sun.tools.javadoc` and some other extinct packages. However, it is unclear if those "references" should also be removed:

1. https://github.com/openjdk/jdk/blob/739769c8fc4b496f08a92225a12d07414537b6c0/test/langtools/tools/javac/NoStringToLower.java#L60-L74
2. https://github.com/openjdk/jdk/blob/739769c8fc4b496f08a92225a12d07414537b6c0/test/langtools/tools/javac/T8003967/DetectMutableStaticFields.java#L73-L85

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Commit messages:
 - Fix issues found by a repaired test
 - Address feedback
 - Initial commit

Changes: https://git.openjdk.java.net/jdk/pull/4192/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4192&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8267708
  Stats: 24 lines in 6 files changed: 1 ins; 13 del; 10 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4192.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4192/head:pull/4192

PR: https://git.openjdk.java.net/jdk/pull/4192