Add SSH SFTP backend support

internal/config/config.go

@@ -14,6 +14,9 @@ type Pipeline struct {
 type Destination struct {
 	ID        string         `yaml:"id"`
 	Backend   string         `yaml:"backend"`
+	Host      string         `yaml:"host"`
+	User      string         `yaml:"user"`
+	Port      int            `yaml:"port"`
 	Path      string         `yaml:"path"`
 	URI       string         `yaml:"uri"`
 	Endpoint  string         `yaml:"endpoint"`
@@ -22,6 +25,7 @@ type Destination struct {
 	Region    string         `yaml:"region"`
 	ForcePath bool           `yaml:"force_path_style"`
 	Creds     Credentials    `yaml:"credentials"`
+	SSH       SSH            `yaml:",inline"`
 	Publish   *PublishPolicy `yaml:"publish"`
 	Transform Transform      `yaml:"transform"`
 	Transfer  TransferPolicy `yaml:"transfer"`
@@ -29,6 +33,9 @@ type Destination struct {
 
 type Backend struct {
 	Backend   string      `yaml:"backend"`
+	Host      string      `yaml:"host"`
+	User      string      `yaml:"user"`
+	Port      int         `yaml:"port"`
 	Path      string      `yaml:"path"`
 	URI       string      `yaml:"uri"`
 	Endpoint  string      `yaml:"endpoint"`
@@ -37,6 +44,13 @@ type Backend struct {
 	Region    string      `yaml:"region"`
 	ForcePath bool        `yaml:"force_path_style"`
 	Creds     Credentials `yaml:"credentials"`
+	SSH       SSH         `yaml:",inline"`
+}
+
+type SSH struct {
+	KeyFile       string        `yaml:"ssh_key_file"`
+	KnownHosts    string        `yaml:"known_hosts"`
+	HostKeyPolicy HostKeyPolicy `yaml:"host_key_policy"`
 }
 
 type Credentials struct {