osbuild2: tar stage

Rename creation function from old assembler and add inputs.

internal/osbuild2/tar_stage.go

@@ -16,11 +16,29 @@ type TarStageOptions struct {
 
 func (TarStageOptions) isStageOptions() {}
 
+type TarStageInput struct {
+	inputCommon
+	References TarStageReferences `json:"references"`
+}
+
+func (TarStageInput) isStageInput() {}
+
+type TarStageInputs struct {
+	Tree *TarStageInput `json:"tree"`
+}
+
+func (TarStageInputs) isStageInputs() {}
+
+type TarStageReferences []string
+
+func (TarStageReferences) isReferences() {}
+
 // Assembles a tree into a tar archive. Compression is determined by the suffix
 // (i.e., --auto-compress is used).
-func NewTarAssembler(options *TarStageOptions) *Stage {
+func NewTarStage(options *TarStageOptions, inputs *TarStageInputs) *Stage {
 	return &Stage{
 		Type:    "org.osbuild.tar",
 		Options: options,
+		Inputs:  inputs,
 	}
 }