RFR: 8322708: Global HTML attributes are not allowed [v6]

[Nizar Benalla]

> Can I please get a review for this change, that aims to add support for Global HTML tags.
> Here is the [link](https://cr.openjdk.org/~nbenalla/javadocGlobalPR/pkg1/package-summary.html) to the generated docs.
> Thanks in advance.

Nizar Benalla has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 12 additional commits since the last revision:

 - Merge branch 'master' into html-attributes
 - whitespace
 - Simplify method
 - Null safety
 - Merge branch 'master' into html-attributes
 - remove trailing whitespace
 - -Add a boolean attribute to the enum type
   -Simply regex in `visitAttribute`
   -Simplified the Test
   -Added a negative test
 - no longer print summary
 - no longer print summary
 - Add small comment
 - ... and 2 more: https://git.openjdk.org/jdk/compare/3c7fc2c1...aa2f2d89

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/19652/files
  - new: https://git.openjdk.org/jdk/pull/19652/files/cfde660d..aa2f2d89

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19652&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19652&range=04-05

  Stats: 4481 lines in 190 files changed: 2834 ins; 1063 del; 584 mod
  Patch: https://git.openjdk.org/jdk/pull/19652.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19652/head:pull/19652

PR: https://git.openjdk.org/jdk/pull/19652