Switch webpushd over to using generated IPC encoder/decoder This will be more secure going forward, and will make future work in this area much simpler. rdar://114886414
Pull request: https://github.com/WebKit/WebKit/pull/17617
Committed 267851@main (70dba30bd03c): <https://commits.webkit.org/267851@main> Reviewed commits have been landed. Closing PR #17617 and removing active labels.