RFR: JDK-8309566: Migrate away from TagletWriter and TagletWriterImpl [v3]

[Jonathan Gibbons]

On Wed, 12 Jul 2023 20:14:58 GMT, Jonathan Gibbons <jjg at openjdk.org> wrote:

>> Good observation.
>
> I looked at this. Ideally, all the `Utils.getBlockTags` methods should return `List<? extends BlockTagTree>` but such a change leaks into the public API at `DocCommentTree.getBlockTags`. This *may* be a hangover related to handling `ErroneousTree`, _but I didn't dig deep enough to find out_.  Yes, `DocCommentParser` may include `ErroneousTree` here.  That's not to say that `Utils` should not filter out those nodes, but this is getting too far afield for this PR.
> 
> Filed: [JDK-8311974](https://bugs.openjdk.org/browse/JDK-8311974) Clean up Utils.getBlockTags

Actually, it was easy enough to fix now.  It helped that `Utils` was filtering out `ErroneousTree` for the filtered lists.

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PR Review Comment: https://git.openjdk.org/jdk/pull/14793#discussion_r1261721313