osbuild2: port tar assembler to new stage

internal/osbuild2/tar_stage.go

@@ -0,0 +1,26 @@
+package osbuild2
+
+type TarStageOptions struct {
+	// Filename for tar archive
+	Filename string `json:"filename"`
+
+	// Enable support for POSIX ACLs
+	ACLs bool `json:"acls,omitempty"`
+
+	// Enable support for SELinux contexts
+	SELinux bool `json:"selinux,omitempty"`
+
+	// Enable support for extended attributes
+	Xattrs bool `json:"xattrs,omitempty"`
+}
+
+func (TarStageOptions) isStageOptions() {}
+
+// Assembles a tree into a tar archive. Compression is determined by the suffix
+// (i.e., --auto-compress is used).
+func NewTarAssembler(options *TarStageOptions) *Stage {
+	return &Stage{
+		Type:    "org.osbuild.tar",
+		Options: options,
+	}
+}