Initial Store & Forward Implementation (#2917)

This adds store & forward relays into dendrite for p2p.
A few things have changed:
- new relay api serves new http endpoints for s&f federation
- updated outbound federation queueing which will attempt to forward
using s&f if appropriate
- database entries to track s&f relays for other nodes

relayapi/internal/api.go

@@ -0,0 +1,53 @@
+// Copyright 2022 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package internal
+
+import (
+	fedAPI "github.com/matrix-org/dendrite/federationapi/api"
+	"github.com/matrix-org/dendrite/federationapi/producers"
+	"github.com/matrix-org/dendrite/relayapi/storage"
+	rsAPI "github.com/matrix-org/dendrite/roomserver/api"
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+type RelayInternalAPI struct {
+	db                     storage.Database
+	fedClient              fedAPI.FederationClient
+	rsAPI                  rsAPI.RoomserverInternalAPI
+	keyRing                *gomatrixserverlib.KeyRing
+	producer               *producers.SyncAPIProducer
+	presenceEnabledInbound bool
+	serverName             gomatrixserverlib.ServerName
+}
+
+func NewRelayInternalAPI(
+	db storage.Database,
+	fedClient fedAPI.FederationClient,
+	rsAPI rsAPI.RoomserverInternalAPI,
+	keyRing *gomatrixserverlib.KeyRing,
+	producer *producers.SyncAPIProducer,
+	presenceEnabledInbound bool,
+	serverName gomatrixserverlib.ServerName,
+) *RelayInternalAPI {
+	return &RelayInternalAPI{
+		db:                     db,
+		fedClient:              fedClient,
+		rsAPI:                  rsAPI,
+		keyRing:                keyRing,
+		producer:               producer,
+		presenceEnabledInbound: presenceEnabledInbound,
+		serverName:             serverName,
+	}
+}