Refactor count-handwritten-decoders to make it easier to add exclusions (and add a few more exclusions)
<rdar://problem/118865137>
Pull request: https://github.com/WebKit/WebKit/pull/20974
Committed 271237@main (26e8252c4b41): <https://commits.webkit.org/271237@main> Reviewed commits have been landed. Closing PR #20974 and removing active labels.