AppleHV - make gz ops sparse

gz by definition is not able to preserve the sparse nature of files.  using some code from the crc project and gluing it together with our decompression code, we can re-create the sparseness of a file.  one downside is the operation is a little bit slower, but i think the gains from the sparse file are well worth it in IO alone.

there are a number of todo's in this PR that would be ripe for quick hitting fixes.

[NO NEW TESTS NEEDED]

Signed-off-by: Brent Baude <baude@redhat.com>

pkg/machine/compression/copy_test.go

@@ -0,0 +1,52 @@
+package compression
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestCopyFile(t *testing.T) {
+	testStr := "test-machine"
+
+	srcFile, err := os.CreateTemp("", "machine-test-")
+	if err != nil {
+		t.Fatal(err)
+	}
+	srcFi, err := srcFile.Stat()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, _ = srcFile.Write([]byte(testStr)) //nolint:mirror
+	srcFile.Close()
+
+	srcFilePath := filepath.Join(os.TempDir(), srcFi.Name())
+
+	destFile, err := os.CreateTemp("", "machine-copy-test-")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	destFi, err := destFile.Stat()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	destFile.Close()
+
+	destFilePath := filepath.Join(os.TempDir(), destFi.Name())
+
+	if err := CopyFile(srcFilePath, destFilePath); err != nil {
+		t.Fatal(err)
+	}
+
+	data, err := os.ReadFile(destFilePath)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if string(data) != testStr {
+		t.Fatalf("expected data \"%s\"; received \"%s\"", testStr, string(data))
+	}
+}