Create empty implementations of Progress(.Factory)

Author: fwcd

server/src/main/kotlin/org/javacs/kt/progress/Progress.kt

@@ -11,12 +11,22 @@ interface Progress : Closeable {
      */
     fun update(message: String? = null, percent: Int? = null)
 
+    object None : Progress {
+        override fun update(message: String?, percent: Int?) {}
+
+        override fun close() {}
+    }
+
     interface Factory {
         /**
          * Creates a new progress listener with
          * the given label. The label is intended
          * to be human-readable.
          */
         fun create(label: String): CompletableFuture<Progress>
+
+        object None : Factory {
+            override fun create(label: String): CompletableFuture<Progress> = CompletableFuture.completedFuture(Progress.None)
+        }
     }
 }