[iOS] Write web archive data using the com.apple.webarchive UTI when copying/dragging

[whsieh]

cb14ef5

[iOS] Write web archive data using the `com.apple.webarchive` UTI when copying/dragging
https://bugs.webkit.org/show_bug.cgi?id=267131
rdar://120545471

Reviewed by Aditya Keerthi.

Publish `com.apple.webarchive` alongside the legacy `Apple Web Archive pasteboard type` when writing
web archive data to the pasteboard when copying or dragging, so that the system can automatically
coerce from web archive data (which may include attachments) to `NSAttributedString`, RTF, or flat
RTFD if needed.

Note that landing this change no longer requires rdar://46830277 to be fixed after the (more recent)
UIKit changes in rdar://116051491, because writing `com.apple.webarchive` data now additionally
registers "derived" types for `public.rtf` and `com.apple.flat-rtfd`. This ensures that Messages
won't prefer pasting text copied in Safari as a `.webarchive` file over plain text in the entry
view.

* Source/WebCore/platform/ios/PlatformPasteboardIOS.mm:
(WebCore::PlatformPasteboard::write):
* Tools/TestWebKitAPI/Tests/ios/DragAndDropTestsIOS.mm:

Additionally rebaseline an API test, to reflect the fact that we should now register
`com.apple.webarchive` when dragging.

Canonical link: https://commits.webkit.org/272697@main

a83158d

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 gtk
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 api-gtk
	✅ 🛠 tv-sim
✅ 🛠 🧪 merge	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash a83158d)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 gtk
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 api-gtk
	✅ 🛠 tv-sim
✅ 🛠 🧪 merge	✅ 🛠 watch
	✅ 🛠 watch-sim

[whsieh]

Thanks for the review!

(It looks like the failing API test, RequiresUserActionForPlaybackTest.DoesNotRequireUserActionForMediaPlayback, is unrelated)

[webkit-commit-queue]

Committed 272697@main (cb14ef5): https://commits.webkit.org/272697@main

Reviewed commits have been landed. Closing PR #22435 and removing active labels.