routerrpc: FailureDetail enums for invoice/AMP validation failures

lnrpc/routerrpc/router.proto

@@ -911,6 +911,11 @@ enum FailureDetail {
     INVALID_KEYSEND = 20;
     MPP_IN_PROGRESS = 21;
     CIRCULAR_ROUTE = 22;
+    INVOICE_ALREADY_SETTLED = 23;
+    HTLC_INVOICE_TYPE_MISMATCH = 24;
+    AMP_ERROR = 25;
+    AMP_RECONSTRUCTION = 26;
+    EXTERNAL_VALIDATION_FAILED = 27;
 }
 
 enum PaymentState {
@@ -1133,4 +1138,4 @@ message FindBaseAliasRequest {
 message FindBaseAliasResponse {
     // The base scid that resulted from the base scid look up.
     uint64 base = 1;
-}
+}