Even more space tweaks (#4588)

* Bring back the button to share a space on iOS 26.

* Remove the setting and disable the space tab on iOS 17.

(The tab bar is broken on iPadOS 17).

ElementX/Sources/UITests/UITestsAppCoordinator.swift

@@ -584,7 +584,6 @@ class MockScreen: Identifiable {
             appSettings.hasRunIdentityConfirmationOnboarding = true
             appSettings.hasRunNotificationPermissionsOnboarding = true
             appSettings.analyticsConsentState = .optedOut
-            appSettings.spacesEnabled = true
             appSettings.hasSeenSpacesAnnouncement = true
             
             let clientProxy = ClientProxyMock(.init(userID: "@mock:client.com",