[iOS] Update SPI headers for iOS 17.4

[emw-apple]

98226f6

[iOS] Update SPI headers for iOS 17.4
https://bugs.webkit.org/show_bug.cgi?id=268210
rdar://problem/121706323

Reviewed by Jonathan Bedard and Alexey Proskuryakov.

Add platform flags for libxpc (which is API as of iOS 17.4+) and for
other SPI that were promoted to API as part of the BrowserEngineKit
introduction. Use them to avoid redeclaring things that are now
publicly available.

Additionally, write new BrowserEngineKit SPI declarations for symbols
that are used in testing and by SPI clients of WebKit.

* Source/WTF/wtf/PlatformHave.h:
* Source/WTF/wtf/spi/cocoa/IOSurfaceSPI.h:
* Source/WTF/wtf/spi/darwin/XPCSPI.h:
* Source/WebCore/PAL/pal/spi/cocoa/AVFoundationSPI.h:
* Source/WebCore/PAL/pal/spi/ios/BrowserEngineKitSPI.h:
* Source/WebKit/Platform/spi/ios/UIKitSPI.h:
* Tools/TestRunnerShared/spi/UIKitSPIForTesting.h:

Canonical link: https://commits.webkit.org/274016@main

82525b0

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
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 gtk-wk2
✅ 🛠 🧪 jsc-arm64	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 api-gtk
	✅ 🛠 tv-sim		✅ 🛠 jsc-armv7
✅ 🛠 🧪 merge	✅ 🛠 watch		✅ 🧪 jsc-armv7-tests
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash 23fd3cc)

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
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 gtk-wk2
✅ 🛠 🧪 jsc-arm64	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 api-gtk
	✅ 🛠 tv-sim		✅ 🛠 jsc-armv7
	✅ 🛠 watch		✅ 🧪 jsc-armv7-tests
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash 82525b0)

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
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 gtk-wk2
✅ 🛠 🧪 jsc-arm64	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 api-gtk
	✅ 🛠 tv-sim		✅ 🛠 jsc-armv7
✅ 🛠 🧪 merge	✅ 🛠 watch		✅ 🧪 jsc-armv7-tests
	✅ 🛠 watch-sim

[webkit-commit-queue]

Committed 274016@main (98226f6): https://commits.webkit.org/274016@main

Reviewed commits have been landed. Closing PR #23345 and removing active labels.