invoicesrpc: format invoices.proto and remove json_name fields

We now use the jsonpb marshaler to convert the RPC responses to
JSON in lncli and REST. The jsonpb has a setting to use the
original name as defined in the proto file and the explicit
json_name definition is not necessary any more.
The jsonpb setting is called OrigName and needs to be true.

lnrpc/invoicesrpc/invoices.proto

@@ -22,26 +22,27 @@ service Invoices {
     canceled, this call will succeed. If the invoice is already settled, it will
     fail.
     */
-    rpc CancelInvoice(CancelInvoiceMsg) returns (CancelInvoiceResp);
+    rpc CancelInvoice (CancelInvoiceMsg) returns (CancelInvoiceResp);
 
     /**
     AddHoldInvoice creates a hold invoice. It ties the invoice to the hash
     supplied in the request.
     */
-    rpc AddHoldInvoice(AddHoldInvoiceRequest) returns (AddHoldInvoiceResp);
- 
+    rpc AddHoldInvoice (AddHoldInvoiceRequest) returns (AddHoldInvoiceResp);
+
     /**
     SettleInvoice settles an accepted invoice. If the invoice is already
     settled, this call will succeed.
     */
-    rpc SettleInvoice(SettleInvoiceMsg) returns (SettleInvoiceResp);
+    rpc SettleInvoice (SettleInvoiceMsg) returns (SettleInvoiceResp);
 }
 
 message CancelInvoiceMsg {
     /// Hash corresponding to the (hold) invoice to cancel.
     bytes payment_hash = 1;
-} 
-message CancelInvoiceResp {}
+}
+message CancelInvoiceResp {
+}
 
 message AddHoldInvoiceRequest {
     /**
@@ -50,49 +51,49 @@ message AddHoldInvoiceRequest {
     field of the encoded payment request if the description_hash field is not
     being used.
     */
-    string memo = 1 [json_name = "memo"];
+    string memo = 1;
 
     /// The hash of the preimage
-    bytes hash = 2 [json_name = "hash"];
+    bytes hash = 2;
 
     /**
     The value of this invoice in satoshis
 
     The fields value and value_msat are mutually exclusive.
     */
-    int64 value = 3 [json_name = "value"];
+    int64 value = 3;
 
     /**
     The value of this invoice in millisatoshis
 
     The fields value and value_msat are mutually exclusive.
     */
-    int64 value_msat = 10 [json_name = "value_msat"];
+    int64 value_msat = 10;
 
     /**
     Hash (SHA-256) of a description of the payment. Used if the description of
     payment (memo) is too long to naturally fit within the description field
     of an encoded payment request.
     */
-    bytes description_hash = 4 [json_name = "description_hash"];
+    bytes description_hash = 4;
 
     /// Payment request expiry time in seconds. Default is 3600 (1 hour).
-    int64 expiry = 5 [json_name = "expiry"];
+    int64 expiry = 5;
 
     /// Fallback on-chain address.
-    string fallback_addr = 6 [json_name = "fallback_addr"];
+    string fallback_addr = 6;
 
     /// Delta to use for the time-lock of the CLTV extended to the final hop.
-    uint64 cltv_expiry = 7 [json_name = "cltv_expiry"];
+    uint64 cltv_expiry = 7;
 
     /**
     Route hints that can each be individually used to assist in reaching the
     invoice's destination.
     */
-    repeated lnrpc.RouteHint route_hints = 8 [json_name = "route_hints"];
+    repeated lnrpc.RouteHint route_hints = 8;
 
     /// Whether this invoice should include routing hints for private channels.
-    bool private = 9 [json_name = "private"];
+    bool private = 9;
 }
 
 message AddHoldInvoiceResp {
@@ -101,19 +102,20 @@ message AddHoldInvoiceResp {
     details of the invoice, the sender has all the data necessary to send a
     payment to the recipient.
     */
-    string payment_request = 1 [json_name = "payment_request"];
+    string payment_request = 1;
 }
 
 message SettleInvoiceMsg {
     /// Externally discovered pre-image that should be used to settle the hold invoice.
     bytes preimage = 1;
-} 
+}
 
-message SettleInvoiceResp {}
+message SettleInvoiceResp {
+}
 
 message SubscribeSingleInvoiceRequest {
     reserved 1;
 
     /// Hash corresponding to the (hold) invoice to subscribe to.
-    bytes r_hash = 2 [json_name = "r_hash"];
+    bytes r_hash = 2;
 }