routerrpc: add UpdateChanStatus RPC to Router service

Update router.proto and rest-annotations.yaml, recompile protos,
add a stub implementation to routerrpc.Server.

lnrpc/routerrpc/router.proto

@@ -121,6 +121,15 @@ service Router {
     */
     rpc HtlcInterceptor (stream ForwardHtlcInterceptResponse)
         returns (stream ForwardHtlcInterceptRequest);
+
+    /*
+    UpdateChanStatus attempts to manually set the state of a channel
+    (enabled, disabled, or auto). A manual "disable" request will cause the
+    channel to stay disabled until a subsequent manual request of either
+    "enable" or "auto".
+    */
+    rpc UpdateChanStatus (UpdateChanStatusRequest)
+        returns (UpdateChanStatusResponse);
 }
 
 message SendPaymentRequest {
@@ -750,3 +759,18 @@ enum ResolveHoldForwardAction {
     FAIL = 1;
     RESUME = 2;
 }
+
+message UpdateChanStatusRequest {
+    lnrpc.ChannelPoint chan_point = 1;
+
+    ChanStatusAction action = 2;
+}
+
+enum ChanStatusAction {
+    ENABLE = 0;
+    DISABLE = 1;
+    AUTO = 2;
+}
+
+message UpdateChanStatusResponse {
+}