Share extension (#3506)

* Setup simple share extension

* Switch the app url scheme to be the full bundle identifier

* Setup a share extension that show a SwiftUI view, uses rust tracing and redirects to the hosting aplication

* Move media as json through the custom scheme into the main app and deep link into the media upload preview screen

* Fix message forwarding and global search screen room summary provider filtering.

* Tweak the message forwarding and global search screen designs.

* Add a room selection screen to use after receiving a share request from the share extension

* Fix share extension entitlements

* Share the temporary directory between the main app and the extensions; rename the caches one.

* Remove the no longer needed notification avatar flipping fix.

* Extract the placeholder avatar image generator from the NSE

* Nest `AvatarSize` within the new `Avatars` enum

* Donate an `INSendMessageIntent` to the system every time we send a message so they appear as share suggestions

* Support suggestions in the share extension itself

* Improve sharing animations and fix presentation when room already on the stack

* Clear all routes when sharing without a preselected room.

* Fix broken unit tests

* Various initial tweaks following code review.

* Correctly clean up and dismiss the share extension for all paths.

* Move the share extension path to a constants enum

* Rename UserSessionFlowCoordinator specific share extension states and events

* Add UserSession and Room flow coordinator share route tests

* Tweak the share extension logic.

ElementX.xcodeproj/xcshareddata/xcschemes/ShareExtension.xcscheme

@@ -0,0 +1,98 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Scheme
+   LastUpgradeVersion = "1430"
+   wasCreatedForAppExtension = "YES"
+   version = "1.7">
+   <BuildAction
+      parallelizeBuildables = "YES"
+      buildImplicitDependencies = "YES"
+      runPostActionsOnFailure = "NO">
+      <BuildActionEntries>
+         <BuildActionEntry
+            buildForTesting = "YES"
+            buildForRunning = "YES"
+            buildForProfiling = "YES"
+            buildForArchiving = "YES"
+            buildForAnalyzing = "YES">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "19F0C845D67E9BEA4BE7133E"
+               BuildableName = "ShareExtension.appex"
+               BlueprintName = "ShareExtension"
+               ReferencedContainer = "container:ElementX.xcodeproj">
+            </BuildableReference>
+         </BuildActionEntry>
+      </BuildActionEntries>
+   </BuildAction>
+   <TestAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      onlyGenerateCoverageForSpecifiedTargets = "NO">
+      <MacroExpansion>
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "19F0C845D67E9BEA4BE7133E"
+            BuildableName = "ShareExtension.appex"
+            BlueprintName = "ShareExtension"
+            ReferencedContainer = "container:ElementX.xcodeproj">
+         </BuildableReference>
+      </MacroExpansion>
+      <Testables>
+      </Testables>
+      <CommandLineArguments>
+      </CommandLineArguments>
+   </TestAction>
+   <LaunchAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = ""
+      selectedLauncherIdentifier = "Xcode.IDEFoundation.Launcher.PosixSpawn"
+      launchStyle = "0"
+      askForAppToLaunch = "YES"
+      useCustomWorkingDirectory = "NO"
+      ignoresPersistentStateOnLaunch = "NO"
+      debugDocumentVersioning = "YES"
+      debugServiceExtension = "internal"
+      allowLocationSimulation = "YES"
+      launchAutomaticallySubstyle = "2">
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "19F0C845D67E9BEA4BE7133E"
+            BuildableName = "ShareExtension.appex"
+            BlueprintName = "ShareExtension"
+            ReferencedContainer = "container:ElementX.xcodeproj">
+         </BuildableReference>
+      </BuildableProductRunnable>
+      <CommandLineArguments>
+      </CommandLineArguments>
+   </LaunchAction>
+   <ProfileAction
+      buildConfiguration = "Release"
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      savedToolIdentifier = ""
+      useCustomWorkingDirectory = "NO"
+      debugDocumentVersioning = "YES">
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "19F0C845D67E9BEA4BE7133E"
+            BuildableName = "ShareExtension.appex"
+            BlueprintName = "ShareExtension"
+            ReferencedContainer = "container:ElementX.xcodeproj">
+         </BuildableReference>
+      </BuildableProductRunnable>
+      <CommandLineArguments>
+      </CommandLineArguments>
+   </ProfileAction>
+   <AnalyzeAction
+      buildConfiguration = "Debug">
+   </AnalyzeAction>
+   <ArchiveAction
+      buildConfiguration = "Release"
+      revealArchiveInOrganizer = "YES">
+   </ArchiveAction>
+</Scheme>