Messenger - backup

• Add functions to Messenger:
  • registerBackupCallback
  • isBackupRunning
  • startBackup
  • resumeBackup
  • stopBackup
  • backupParams
• Update docs
• Prevent backups without params

Sources/XXMessengerClient/Messenger/Functions/MessengerStopBackup.swift

+import Bindings
+import XCTestDynamicOverlay
+
+public struct MessengerStopBackup {
+  public var run: () throws -> Void
+
+  public func callAsFunction() throws {
+    try run()
+  }
+}
+
+extension MessengerStopBackup {
+  public static func live(_ env: MessengerEnvironment) -> MessengerStopBackup {
+    MessengerStopBackup {
+      guard let backup = env.backup() else { return }
+      try backup.stop()
+      env.backup.set(nil)
+    }
+  }
+}
+
+extension MessengerStopBackup {
+  public static let unimplemented = MessengerStopBackup(
+    run: XCTUnimplemented("\(Self.self)")
+  )
+}