lnrpc: update routerrpc to use the new status

lnrpc/lightning.proto

@@ -3903,10 +3903,20 @@ message Payment {
     string payment_request = 9;
 
     enum PaymentStatus {
-        UNKNOWN = 0;
+        // Deprecated. This status will never be returned.
+        UNKNOWN = 0 [deprecated = true];
+
+        // Payment has inflight HTLCs.
         IN_FLIGHT = 1;
+
+        // Payment is settled.
         SUCCEEDED = 2;
+
+        // Payment is failed.
         FAILED = 3;
+
+        // Payment is created and has not attempted any HTLCs.
+        INITIATED = 4;
     }
 
     // The status of the payment.

lnrpc/lightning.swagger.json

@@ -2876,9 +2876,11 @@
         "UNKNOWN",
         "IN_FLIGHT",
         "SUCCEEDED",
-        "FAILED"
+        "FAILED",
+        "INITIATED"
       ],
-      "default": "UNKNOWN"
+      "default": "UNKNOWN",
+      "description": " - UNKNOWN: Deprecated. This status will never be returned.\n - IN_FLIGHT: Payment has inflight HTLCs.\n - SUCCEEDED: Payment is settled.\n - FAILED: Payment is failed.\n - INITIATED: Payment is created and has not attempted any HTLCs."
     },
     "PeerEventEventType": {
       "type": "string",

lnrpc/routerrpc/router.swagger.json

@@ -1015,9 +1015,11 @@
         "UNKNOWN",
         "IN_FLIGHT",
         "SUCCEEDED",
-        "FAILED"
+        "FAILED",
+        "INITIATED"
       ],
-      "default": "UNKNOWN"
+      "default": "UNKNOWN",
+      "description": " - UNKNOWN: Deprecated. This status will never be returned.\n - IN_FLIGHT: Payment has inflight HTLCs.\n - SUCCEEDED: Payment is settled.\n - FAILED: Payment is failed.\n - INITIATED: Payment is created and has not attempted any HTLCs."
     },
     "lnrpcRoute": {
       "type": "object",

lnrpc/routerrpc/router_backend.go

@@ -1370,6 +1370,9 @@ func convertPaymentStatus(dbStatus channeldb.PaymentStatus) (
 	lnrpc.Payment_PaymentStatus, error) {
 
 	switch dbStatus {
+	case channeldb.StatusInitiated:
+		return lnrpc.Payment_INITIATED, nil
+
 	case channeldb.StatusInFlight:
 		return lnrpc.Payment_IN_FLIGHT, nil