MySQL peer (#1637)

Currently testing with [mariadb](https://hub.docker.com/_/mariadb)
```
CREATE PEER my FROM MYSQL WITH (
  host = 'mysql',
  port = '3306',
  user = 'root',
  password = 'example',
  database = 'main',
  compression = 1,
  disable_tls = true
);
```

The scope of this PR is only peer creation & nexus proxy. No mirror support

Co-authored-by: Kaushik Iska <[email protected]>

flow/connectors/core.go

@@ -13,6 +13,7 @@ import (
 	connelasticsearch "github.com/PeerDB-io/peer-flow/connectors/connelasticsearch"
 	conneventhub "github.com/PeerDB-io/peer-flow/connectors/eventhub"
 	connkafka "github.com/PeerDB-io/peer-flow/connectors/kafka"
+	connmysql "github.com/PeerDB-io/peer-flow/connectors/mysql"
 	connpostgres "github.com/PeerDB-io/peer-flow/connectors/postgres"
 	connpubsub "github.com/PeerDB-io/peer-flow/connectors/pubsub"
 	conns3 "github.com/PeerDB-io/peer-flow/connectors/s3"
@@ -224,14 +225,14 @@ func GetConnector(ctx context.Context, config *protos.Peer) (Connector, error) {
 		return connbigquery.NewBigQueryConnector(ctx, inner.BigqueryConfig)
 	case *protos.Peer_SnowflakeConfig:
 		return connsnowflake.NewSnowflakeConnector(ctx, inner.SnowflakeConfig)
-	case *protos.Peer_EventhubConfig:
-		return nil, errors.New("use eventhub group config instead")
 	case *protos.Peer_EventhubGroupConfig:
 		return conneventhub.NewEventHubConnector(ctx, inner.EventhubGroupConfig)
 	case *protos.Peer_S3Config:
 		return conns3.NewS3Connector(ctx, inner.S3Config)
 	case *protos.Peer_SqlserverConfig:
 		return connsqlserver.NewSQLServerConnector(ctx, inner.SqlserverConfig)
+	case *protos.Peer_MysqlConfig:
+		return connmysql.MySqlConnector{}, nil
 	case *protos.Peer_ClickhouseConfig:
 		return connclickhouse.NewClickhouseConnector(ctx, inner.ClickhouseConfig)
 	case *protos.Peer_KafkaConfig:
@@ -341,4 +342,6 @@ var (
 	_ ValidationConnector = &connclickhouse.ClickhouseConnector{}
 	_ ValidationConnector = &connbigquery.BigQueryConnector{}
 	_ ValidationConnector = &conns3.S3Connector{}
+
+	_ Connector = &connmysql.MySqlConnector{}
 )

flow/connectors/mysql/mysql.go

@@ -0,0 +1,15 @@
+// stub to bypass validation
+
+package mysql
+
+import "context"
+
+type MySqlConnector struct{}
+
+func (MySqlConnector) Close() error {
+	return nil
+}
+
+func (MySqlConnector) ConnectionActive(context.Context) error {
+	return nil
+}