Fix the flakey preview tests. (#4329)

* Try fix the flakey preview tests with a low priority task…

* Try RunLoop.current.perform

* Revert #4321: Use a dispatch queue again. Also fixes the concurrency warning with a Mutex.

The Mutex package is only required for iOS 17, we can remove it when we set the minimum deployment target to iOS 18.

ElementX/SupportingFiles/Settings.bundle/Acknowledgements.plist

@@ -194,6 +194,14 @@
 			<key>Type</key>
 			<string>PSChildPaneSpecifier</string>
 		</dict>
+		<dict>
+			<key>File</key>
+			<string>Packages/swift-mutex</string>
+			<key>Title</key>
+			<string>swift-mutex</string>
+			<key>Type</key>
+			<string>PSChildPaneSpecifier</string>
+		</dict>
 		<dict>
 			<key>File</key>
 			<string>Packages/swift-numerics</string>

ElementX/SupportingFiles/Settings.bundle/Packages/swift-mutex.plist

@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>PreferenceSpecifiers</key>
+	<array>
+		<dict>
+			<key>FooterText</key>
+			<string>MIT License
+
+Copyright (c) 2023 Simon Whitty
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+</string>
+			<key>Type</key>
+			<string>PSGroupSpecifier</string>
+		</dict>
+	</array>
+</dict>
+</plist>

ElementX/SupportingFiles/target.yml

@@ -235,6 +235,7 @@ targets:
     - package: LoremSwiftum
     - package: LRUCache
     - package: Mapbox
+    - package: Mutex
     - package: PostHog
     - package: SwiftState
     - package: GZIP