Add GetTransactionsStream RPC (#345)

* RPC GetPaymentsStream

This introduces a new feature to the ArkService API that allows clients to subscribe to payment events. Here's a breakdown of the changes:

1. **OpenAPI Specification (`service.swagger.json`):**
   - A new endpoint `/v1/payments` is added to the API, supporting a `GET` operation for streaming payment events.
   - New definitions `v1GetPaymentsStreamResponse`, `v1RoundPayment`, and `v1AsyncPayment` are added to describe the structure of the streaming responses.

2. **Protobuf Definition (`service.proto`):**
   - Added a new RPC method `GetPaymentsStream` that streams `GetPaymentsStreamResponse` messages.
   - Defined new message types: `GetPaymentsStreamRequest`, `GetPaymentsStreamResponse`, `RoundPayment`, and `AsyncPayment`.

3. **Generated Protobuf Code (`service.pb.go`, `service.pb.gw.go`, `service_grpc.pb.go`):**
   - The generated code is updated to include the new RPC method and message types.
   - The gateway code includes functions to handle HTTP requests and responses for the new streaming endpoint.

4. **Application Logic (`covenant.go`, `covenantless.go`):**
   - New payment events channels are introduced (`paymentEventsCh`).
   - Payment events are propagated to these channels when a round is finalized or an async payment is completed.
   - New event types `RoundPaymentEvent` and `AsyncPaymentEvent` are defined, implementing a `PaymentEvent` interface.

5. **gRPC Handlers (`arkservice.go`):**
   - Added logic to handle `GetPaymentsStream` requests and manage payment listeners.
   - A new goroutine is started to listen to payment events and forward them to active listeners.

Overall, this patch extends the ArkService to support real-time streaming of payment events, allowing clients to receive updates on both round payments and async payments as they occur.

* Move emit events in updateVtxoSet & Use generics and parsers (#1)

* Move sending event to updateVtxoSet

* Use generics and parsers

* pr review refactor

* pr review refactor

* fix

---------

Co-authored-by: Pietralberto Mazza <18440657+altafan@users.noreply.github.com>

server/internal/interface/grpc/handlers/parser.go

@@ -92,6 +92,19 @@ func (v vtxoList) toProto() []*arkv1.Vtxo {
 	return list
 }
 
+type vtxoKeyList []domain.VtxoKey
+
+func (v vtxoKeyList) toProto() []*arkv1.Outpoint {
+	list := make([]*arkv1.Outpoint, 0, len(v))
+	for _, vtxoKey := range v {
+		list = append(list, &arkv1.Outpoint{
+			Txid: vtxoKey.Txid,
+			Vout: vtxoKey.VOut,
+		})
+	}
+	return list
+}
+
 type congestionTree tree.CongestionTree
 
 func (t congestionTree) toProto() *arkv1.Tree {