lnrpc: update grpc-gateway library to v2

lnrpc/lnclipb/lncli.pb.go

@@ -1,13 +1,12 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.23.0
+// 	protoc-gen-go v1.26.0
 // 	protoc        v3.6.1
 // source: lnclipb/lncli.proto
 
 package lnclipb
 
 import (
-	proto "github.com/golang/protobuf/proto"
 	verrpc "github.com/lightningnetwork/lnd/lnrpc/verrpc"
 	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
@@ -22,10 +21,6 @@ const (
 	_ = protoimpl.EnforceVersion(protoimpl.MaxVersion - 20)
 )
 
-// This is a compile-time assertion that a sufficiently up-to-date version
-// of the legacy proto package is being used.
-const _ = proto.ProtoPackageIsVersion4
-
 type VersionResponse struct {
 	state         protoimpl.MessageState
 	sizeCache     protoimpl.SizeCache

lnrpc/lnclipb/lncli.swagger.json

@@ -24,12 +24,9 @@
         }
       }
     },
-    "runtimeError": {
+    "rpcStatus": {
       "type": "object",
       "properties": {
-        "error": {
-          "type": "string"
-        },
         "code": {
           "type": "integer",
           "format": "int32"