Add WKApplicationManifest API Similar to _WKApplicationManifest, but not a straight up promotion from SPI - WKApplicationManifest is not meant to be constructible by API clients rdar://104630943
Pull request: https://github.com/WebKit/WebKit/pull/9259
Committed 259523@main (275b520c9428): <https://commits.webkit.org/259523@main> Reviewed commits have been landed. Closing PR #9259 and removing active labels.
Re-opened since this is blocked by bug 251525