osbuild: add ostree.commit assembler

This adds the wrapper object and a simple test for the ostree.commit
assembler.

See the osbuild documentation for details.

Signed-off-by: Tom Gundersen <teg@jklm.no>

internal/osbuild/ostree_commit_assembler.go

@@ -0,0 +1,23 @@
+package osbuild
+
+// OSTreeCommitAssemblerOptions desrcibe how to assemble a tree into an OSTree commit.
+type OSTreeCommitAssemblerOptions struct {
+	Ref    string                          `json:"ref"`
+	Parent string                          `json:"parent,omitempty"`
+	Tar    OSTreeCommitAssemblerTarOptions `json:"tar"`
+}
+
+// OSTreeCommitAssemblerTarOptions desrcibes the output tarball
+type OSTreeCommitAssemblerTarOptions struct {
+	Filename string `json:"filename"`
+}
+
+func (OSTreeCommitAssemblerOptions) isAssemblerOptions() {}
+
+// NewOSTreeCommitAssembler creates a new OSTree Commit Assembler object.
+func NewOSTreeCommitAssembler(options *OSTreeCommitAssemblerOptions) *Assembler {
+	return &Assembler{
+		Name:    "org.osbuild.ostree.commit",
+		Options: options,
+	}
+}