RFR: JDK-8312445: Array types in annotation elements show square brackets twice

[Hannes Wallnöfer]

Please review a change to fix the representation of array types as values of annotation elements in javadoc-generated documentation.

The primary fix is to avoid generating duplicate `[]` brackets for array types, but there are a few secondary improvements:

 - When linking to a type, only use the type name as link label, appending the `.class` as plain text after the link
 - Support linking to the base type of array types, again appending the square brackets and `.class` after the link
 - Leave it to the `LinkFactory` code to decide whether to use the qualified or simple type name for a link (uses `isLinkable` instead of `isIncluded`)

There already was some test code for the use of array types in annotation elements in `TestNewLanguageFeatures.java`, but it was disabled with a comment referring to another issue that has long been resolved.

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Commit messages:
 - JDK-8312445: Array types in annotation elements show square brackets twice

Changes: https://git.openjdk.org/jdk/pull/15019/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15019&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8312445
  Stats: 38 lines in 4 files changed: 18 ins; 6 del; 14 mod
  Patch: https://git.openjdk.org/jdk/pull/15019.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15019/head:pull/15019

PR: https://git.openjdk.org/jdk/pull/15019