RFR: JDK-8326332: Unclosed inline tags cause misalignment in summary tables

[Hannes Wallnöfer]

Please review a simple fix to make sure inline tags are always closed in summary tables, even when the tags are closed after the first sentence in the original doc comment. 

I decided to colocate the functionality to track open inline tags with the existing `ignoreNonInlineTag` method that filters out non-inline elements because there is a lot of common functionality, such as retrieving the name and kind of an HTML tag. I considered giving the method a name that describes the additional functionality, but couldn't find one that wasn't comically long. Suggestions are welcome of course.

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Commit messages:
 - JDK-8326332: Unclosed inline tags cause misalignment in summary tables

Changes: https://git.openjdk.org/jdk/pull/18154/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18154&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8326332
  Stats: 39 lines in 3 files changed: 26 ins; 1 del; 12 mod
  Patch: https://git.openjdk.org/jdk/pull/18154.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18154/head:pull/18154

PR: https://git.openjdk.org/jdk/pull/18154