Tunnel: Remove UNKNOWN state

It's never used.

Signed-off-by: Samuel Holland <samuel@sholland.org>

app/src/main/java/com/wireguard/android/backend/WgQuickBackend.java

@@ -35,8 +35,6 @@ public final class WgQuickBackend implements Backend {
     }
 
     private static State resolveState(final State currentState, State requestedState) {
-        if (requestedState == State.UNKNOWN)
-            throw new IllegalArgumentException("Requested unknown state");
         if (requestedState == State.TOGGLE)
             requestedState = currentState == State.UP ? State.DOWN : State.UP;
         return requestedState;

app/src/main/java/com/wireguard/android/model/Tunnel.java

@@ -69,15 +69,11 @@ public class Tunnel extends BaseObservable implements Keyed<String> {
 
     @Bindable
     public State getState() {
-        if (state == State.UNKNOWN)
-            manager.getTunnelState(this).whenComplete(ExceptionLoggers.E);
         return state;
     }
 
     public CompletionStage<State> getStateAsync() {
-        if (state == State.UNKNOWN)
-            return manager.getTunnelState(this);
-        return CompletableFuture.completedFuture(state);
+        return manager.getTunnelState(this);
     }
 
     @Bindable
@@ -133,7 +129,6 @@ public class Tunnel extends BaseObservable implements Keyed<String> {
     public enum State {
         DOWN,
         TOGGLE,
-        UNKNOWN,
         UP
     }