macOS: Edit view: Save on Cmd+S

Signed-off-by: Roopesh Chander <roop@roopc.net>

WireGuard/WireGuard/UI/macOS/ViewController/TunnelEditViewController.swift

@@ -73,6 +73,8 @@ class TunnelEditViewController: NSViewController {
         button.title = tr("macEditSave")
         button.setButtonType(.momentaryPushIn)
         button.bezelStyle = .rounded
+        button.keyEquivalent = "s"
+        button.keyEquivalentModifierMask = [.command]
         return button
     }()